diff --git a/docs/api-generated/cases/case-apis-passthru.asciidoc b/docs/api-generated/cases/case-apis-passthru.asciidoc
index d10933c5b0a9c..2ccee8484b882 100644
--- a/docs/api-generated/cases/case-apis-passthru.asciidoc
+++ b/docs/api-generated/cases/case-apis-passthru.asciidoc
@@ -87,6 +87,11 @@ Any modifications made to this file will be overwritten.
   "totalAlerts" : 0,
   "closed_at" : "2000-01-23T04:56:07.000+00:00",
   "comments" : [ null, null ],
+  "assignees" : [ {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  }, {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  } ],
   "created_at" : "2022-05-13T09:16:17.416Z",
   "description" : "A case description.",
   "title" : "Case title 1",
@@ -199,6 +204,11 @@ Any modifications made to this file will be overwritten.
   "totalAlerts" : 0,
   "closed_at" : "2000-01-23T04:56:07.000+00:00",
   "comments" : [ null, null ],
+  "assignees" : [ {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  }, {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  } ],
   "created_at" : "2022-05-13T09:16:17.416Z",
   "description" : "A case description.",
   "title" : "Case title 1",
@@ -376,6 +386,11 @@ Any modifications made to this file will be overwritten.
   "totalAlerts" : 0,
   "closed_at" : "2000-01-23T04:56:07.000+00:00",
   "comments" : [ null, null ],
+  "assignees" : [ {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  }, {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  } ],
   "created_at" : "2022-05-13T09:16:17.416Z",
   "description" : "A case description.",
   "title" : "Case title 1",
@@ -488,6 +503,11 @@ Any modifications made to this file will be overwritten.
   "totalAlerts" : 0,
   "closed_at" : "2000-01-23T04:56:07.000+00:00",
   "comments" : [ null, null ],
+  "assignees" : [ {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  }, {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  } ],
   "created_at" : "2022-05-13T09:16:17.416Z",
   "description" : "A case description.",
   "title" : "Case title 1",
@@ -602,6 +622,11 @@ Any modifications made to this file will be overwritten.
   "totalAlerts" : 0,
   "closed_at" : "2000-01-23T04:56:07.000+00:00",
   "comments" : [ null, null ],
+  "assignees" : [ {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  }, {
+    "uid" : "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+  } ],
   "created_at" : "2022-05-13T09:16:17.416Z",
   "description" : "A case description.",
   "title" : "Case title 1",
@@ -677,6 +702,7 @@ Any modifications made to this file will be overwritten.
     <li><a href="#case_response_closed_by_properties"><code>case_response_closed_by_properties</code> - Case response properties for closed_by</a></li>
     <li><a href="#case_response_created_by_properties"><code>case_response_created_by_properties</code> - Case response properties for created_by</a></li>
     <li><a href="#case_response_properties"><code>case_response_properties</code> - Case response properties</a></li>
+    <li><a href="#case_response_properties_assignees_inner"><code>case_response_properties_assignees_inner</code> - </a></li>
     <li><a href="#case_response_pushed_by_properties"><code>case_response_pushed_by_properties</code> - Case response properties for pushed_by</a></li>
     <li><a href="#case_response_updated_by_properties"><code>case_response_updated_by_properties</code> - Case response properties for updated_by</a></li>
     <li><a href="#connector_properties_cases_webhook"><code>connector_properties_cases_webhook</code> - Create or upate case request properties for Cases Webhook connector</a></li>
@@ -692,6 +718,7 @@ Any modifications made to this file will be overwritten.
     <li><a href="#connector_properties_swimlane"><code>connector_properties_swimlane</code> - Create case request properties for a Swimlane connector</a></li>
     <li><a href="#connector_properties_swimlane_fields"><code>connector_properties_swimlane_fields</code> - </a></li>
     <li><a href="#create_case_request"><code>create_case_request</code> - Create case request</a></li>
+    <li><a href="#create_case_request_assignees_inner"><code>create_case_request_assignees_inner</code> - </a></li>
     <li><a href="#create_case_request_connector"><code>create_case_request_connector</code> - </a></li>
     <li><a href="#external_service"><code>external_service</code> - </a></li>
     <li><a href="#owners"><code>owners</code> - </a></li>
@@ -864,7 +891,8 @@ Any modifications made to this file will be overwritten.
     <h3><a name="case_response_properties"><code>case_response_properties</code> - Case response properties</a> <a class="up" href="#__Models">Up</a></h3>
     <div class='model-description'></div>
     <div class="field-items">
-      <div class="param">closed_at </div><div class="param-desc"><span class="param-type"><a href="#DateTime">Date</a></span>  format: date-time</div>
+      <div class="param">assignees (optional)</div><div class="param-desc"><span class="param-type"><a href="#case_response_properties_assignees_inner">array[case_response_properties_assignees_inner]</a></span> An array containing users that are assigned to the case. </div>
+<div class="param">closed_at </div><div class="param-desc"><span class="param-type"><a href="#DateTime">Date</a></span>  format: date-time</div>
 <div class="param">closed_by </div><div class="param-desc"><span class="param-type"><a href="#case_response_closed_by_properties">case_response_closed_by_properties</a></span>  </div>
 <div class="param">comments </div><div class="param-desc"><span class="param-type"><a href="#Case_response_properties_for_comments_inner">array[Case_response_properties_for_comments_inner]</a></span> An array of comment objects for the case. </div>
 <div class="param">connector </div><div class="param-desc"><span class="param-type"><a href="#Case_response_properties_for_connectors">Case_response_properties_for_connectors</a></span>  </div>
@@ -887,6 +915,13 @@ Any modifications made to this file will be overwritten.
 <div class="param">version </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span>  </div>
     </div>  <!-- field-items -->
   </div>
+  <div class="model">
+    <h3><a name="case_response_properties_assignees_inner"><code>case_response_properties_assignees_inner</code> - </a> <a class="up" href="#__Models">Up</a></h3>
+    <div class='model-description'></div>
+    <div class="field-items">
+      <div class="param">uid </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> A unique identifier for the user profile. You can use the get user profile API to retrieve more details. </div>
+    </div>  <!-- field-items -->
+  </div>
   <div class="model">
     <h3><a name="case_response_pushed_by_properties"><code>case_response_pushed_by_properties</code> - Case response properties for pushed_by</a> <a class="up" href="#__Models">Up</a></h3>
     <div class='model-description'></div>
@@ -1043,7 +1078,8 @@ Any modifications made to this file will be overwritten.
     <h3><a name="create_case_request"><code>create_case_request</code> - Create case request</a> <a class="up" href="#__Models">Up</a></h3>
     <div class='model-description'>The create case API request body varies depending on the type of connector.</div>
     <div class="field-items">
-      <div class="param">connector </div><div class="param-desc"><span class="param-type"><a href="#create_case_request_connector">create_case_request_connector</a></span>  </div>
+      <div class="param">assignees (optional)</div><div class="param-desc"><span class="param-type"><a href="#create_case_request_assignees_inner">array[create_case_request_assignees_inner]</a></span> An array containing users that are assigned to the case. </div>
+<div class="param">connector </div><div class="param-desc"><span class="param-type"><a href="#create_case_request_connector">create_case_request_connector</a></span>  </div>
 <div class="param">description </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> The description for the case. </div>
 <div class="param">owner </div><div class="param-desc"><span class="param-type"><a href="#owners">owners</a></span>  </div>
 <div class="param">settings </div><div class="param-desc"><span class="param-type"><a href="#settings">settings</a></span>  </div>
@@ -1052,6 +1088,13 @@ Any modifications made to this file will be overwritten.
 <div class="param">title </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> A title for the case. </div>
     </div>  <!-- field-items -->
   </div>
+  <div class="model">
+    <h3><a name="create_case_request_assignees_inner"><code>create_case_request_assignees_inner</code> - </a> <a class="up" href="#__Models">Up</a></h3>
+    <div class='model-description'></div>
+    <div class="field-items">
+      <div class="param">uid </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API. </div>
+    </div>  <!-- field-items -->
+  </div>
   <div class="model">
     <h3><a name="create_case_request_connector"><code>create_case_request_connector</code> - </a> <a class="up" href="#__Models">Up</a></h3>
     <div class='model-description'></div>
@@ -1152,7 +1195,8 @@ Any modifications made to this file will be overwritten.
     <h3><a name="update_case_request_cases_inner"><code>update_case_request_cases_inner</code> - </a> <a class="up" href="#__Models">Up</a></h3>
     <div class='model-description'></div>
     <div class="field-items">
-      <div class="param">connector (optional)</div><div class="param-desc"><span class="param-type"><a href="#create_case_request_connector">create_case_request_connector</a></span>  </div>
+      <div class="param">assignees (optional)</div><div class="param-desc"><span class="param-type"><a href="#create_case_request_assignees_inner">array[create_case_request_assignees_inner]</a></span> An array containing users that are assigned to the case. </div>
+<div class="param">connector (optional)</div><div class="param-desc"><span class="param-type"><a href="#create_case_request_connector">create_case_request_connector</a></span>  </div>
 <div class="param">description (optional)</div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> An updated description for the case. </div>
 <div class="param">id </div><div class="param-desc"><span class="param-type"><a href="#string">String</a></span> The identifier for the case. </div>
 <div class="param">settings (optional)</div><div class="param-desc"><span class="param-type"><a href="#settings">settings</a></span>  </div>
diff --git a/docs/api/cases/cases-api-create.asciidoc b/docs/api/cases/cases-api-create.asciidoc
index 5eec612d8bfca..f124d3500228c 100644
--- a/docs/api/cases/cases-api-create.asciidoc
+++ b/docs/api/cases/cases-api-create.asciidoc
@@ -34,6 +34,18 @@ default space is used.
 [role="child_attributes"]
 === {api-request-body-title}
 
+`assignees`::
+(Optional, array of objects) Array containing users that are assigned to the case.
++
+.Properties of assignee objects
+[%collapsible%open]
+=====
+`uid`:: 
+(Required, string) A unique identifier for the user profile. These identifiers
+can be found by using the
+{ref}/security-api-suggest-user-profile.html[suggest user profile API].
+=====
+
 `connector`::
 (Required, object) An object that contains the connector configuration.
 +
@@ -207,6 +219,7 @@ the case identifier, version, and creation time. For example:
   "totalAlerts": 0,
   "title": "Case title 1",
   "tags": [ "tag 1" ],
+  "assignees": [],
   "settings": {
     "syncAlerts": true
   },
diff --git a/docs/api/cases/cases-api-find-cases.asciidoc b/docs/api/cases/cases-api-find-cases.asciidoc
index d7ae5fed35b0f..770e1d30ee594 100644
--- a/docs/api/cases/cases-api-find-cases.asciidoc
+++ b/docs/api/cases/cases-api-find-cases.asciidoc
@@ -141,6 +141,7 @@ The API returns a JSON object listing the retrieved cases. For example:
         "full_name": "Joe Smith",
         "username": "jsmith"
       },
+      "assignees": [],
       "connector": {
         "id": "none",
         "name": "none",
diff --git a/docs/api/cases/cases-api-get-case.asciidoc b/docs/api/cases/cases-api-get-case.asciidoc
index d7bc316a7346d..9d43afb695a79 100644
--- a/docs/api/cases/cases-api-get-case.asciidoc
+++ b/docs/api/cases/cases-api-get-case.asciidoc
@@ -86,6 +86,7 @@ The API returns a JSON object with the retrieved case. For example:
   "status":"open",
   "updated_at":"2022-07-13T15:40:32.335Z",
   "updated_by":{"full_name":null,"email":null,"username":"elastic"},
+  "assignees":[{"uid":"u_mGBROF_q5bmFCATbLXAcCwKa0k8JvONAwSruelyKA5E_0"}],
   "connector":{"id":"none","name":"none","type":".none","fields":null},
   "external_service":null
 }
diff --git a/docs/api/cases/cases-api-update.asciidoc b/docs/api/cases/cases-api-update.asciidoc
index 30c482da4282c..ca75e34597afc 100644
--- a/docs/api/cases/cases-api-update.asciidoc
+++ b/docs/api/cases/cases-api-update.asciidoc
@@ -40,6 +40,19 @@ default space is used.
 .Properties of `cases` objects
 [%collapsible%open]
 ====
+
+`assignees`::
+(Optional, array of objects) Array containing users that are assigned to the case.
++
+.Properties of assignee objects
+[%collapsible%open]
+=====
+`uid`::
+(Required, string) A unique identifier for the user profile. These identifiers
+can be found by using the
+{ref}/security-api-suggest-user-profile.html[suggest user profile API].
+=====
+
 `connector`::
 (Optional, object) An object that contains the connector configuration.
 +
@@ -203,6 +216,7 @@ PATCH api/cases
       },
       "description": "A new description.",
       "tags": [ "tag-1", "tag-2" ],
+      "assignees": [],
       "settings": {
         "syncAlerts": true
       }
diff --git a/x-pack/plugins/cases/docs/openapi/bundled-min.json b/x-pack/plugins/cases/docs/openapi/bundled-min.json
index 02e04d2b2fbdd..a3f9567b32b3d 100644
--- a/x-pack/plugins/cases/docs/openapi/bundled-min.json
+++ b/x-pack/plugins/cases/docs/openapi/bundled-min.json
@@ -816,6 +816,24 @@
           "title"
         ],
         "properties": {
+          "assignees": {
+            "type": "array",
+            "description": "An array containing users that are assigned to the case.",
+            "nullable": true,
+            "items": {
+              "type": "object",
+              "required": [
+                "uid"
+              ],
+              "properties": {
+                "uid": {
+                  "type": "string",
+                  "description": "A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.",
+                  "example": "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+                }
+              }
+            }
+          },
           "connector": {
             "oneOf": [
               {
@@ -1272,6 +1290,24 @@
           "version"
         ],
         "properties": {
+          "assignees": {
+            "type": "array",
+            "description": "An array containing users that are assigned to the case.",
+            "nullable": true,
+            "items": {
+              "type": "object",
+              "required": [
+                "uid"
+              ],
+              "properties": {
+                "uid": {
+                  "type": "string",
+                  "description": "A unique identifier for the user profile. You can use the get user profile API to retrieve more details.",
+                  "example": "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+                }
+              }
+            }
+          },
           "closed_at": {
             "type": "string",
             "format": "date-time",
@@ -1417,6 +1453,24 @@
                 "version"
               ],
               "properties": {
+                "assignees": {
+                  "type": "array",
+                  "description": "An array containing users that are assigned to the case.",
+                  "nullable": true,
+                  "items": {
+                    "type": "object",
+                    "required": [
+                      "uid"
+                    ],
+                    "properties": {
+                      "uid": {
+                        "type": "string",
+                        "description": "A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.",
+                        "example": "u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0"
+                      }
+                    }
+                  }
+                },
                 "connector": {
                   "oneOf": [
                     {
@@ -1746,6 +1800,7 @@
           "tags": [
             "tag 1"
           ],
+          "assignees": [],
           "description": "A case description.",
           "settings": {
             "syncAlerts": false
@@ -1840,6 +1895,7 @@
               "full_name": null,
               "username": "elastic"
             },
+            "assignees": [],
             "connector": {
               "id": "131d4448-abe0-4789-939d-8ef60680b498",
               "name": "My connector",
diff --git a/x-pack/plugins/cases/docs/openapi/bundled-min.yaml b/x-pack/plugins/cases/docs/openapi/bundled-min.yaml
index d90783ccb7309..43962944ee9f7 100644
--- a/x-pack/plugins/cases/docs/openapi/bundled-min.yaml
+++ b/x-pack/plugins/cases/docs/openapi/bundled-min.yaml
@@ -560,6 +560,19 @@ components:
         - tags
         - title
       properties:
+        assignees:
+          type: array
+          description: An array containing users that are assigned to the case.
+          nullable: true
+          items:
+            type: object
+            required:
+              - uid
+            properties:
+              uid:
+                type: string
+                description: A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.
+                example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
         connector:
           oneOf:
             - $ref: '#/components/schemas/connector_properties_none'
@@ -896,6 +909,19 @@ components:
         - updated_by
         - version
       properties:
+        assignees:
+          type: array
+          description: An array containing users that are assigned to the case.
+          nullable: true
+          items:
+            type: object
+            required:
+              - uid
+            properties:
+              uid:
+                type: string
+                description: A unique identifier for the user profile. You can use the get user profile API to retrieve more details.
+                example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
         closed_at:
           type: string
           format: date-time
@@ -992,6 +1018,19 @@ components:
               - id
               - version
             properties:
+              assignees:
+                type: array
+                description: An array containing users that are assigned to the case.
+                nullable: true
+                items:
+                  type: object
+                  required:
+                    - uid
+                  properties:
+                    uid:
+                      type: string
+                      description: A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.
+                      example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
               connector:
                 oneOf:
                   - $ref: '#/components/schemas/connector_properties_none'
@@ -1222,6 +1261,7 @@ components:
         title: Case title 1
         tags:
           - tag 1
+        assignees: []
         description: A case description.
         settings:
           syncAlerts: false
@@ -1296,6 +1336,7 @@ components:
             email: null
             full_name: null
             username: elastic
+          assignees: []
           connector:
             id: 131d4448-abe0-4789-939d-8ef60680b498
             name: My connector
diff --git a/x-pack/plugins/cases/docs/openapi/components/examples/create_case_response.yaml b/x-pack/plugins/cases/docs/openapi/components/examples/create_case_response.yaml
index 7d9cdf3626c72..8cd80595abf30 100644
--- a/x-pack/plugins/cases/docs/openapi/components/examples/create_case_response.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/examples/create_case_response.yaml
@@ -8,6 +8,7 @@ value:
   title: Case title 1
   tags:
     - tag 1
+  assignees: []
   description: A case description.
   settings:
     syncAlerts: false
diff --git a/x-pack/plugins/cases/docs/openapi/components/examples/find_case_response.yaml b/x-pack/plugins/cases/docs/openapi/components/examples/find_case_response.yaml
index 1c8168dde7708..6f744d03a1365 100644
--- a/x-pack/plugins/cases/docs/openapi/components/examples/find_case_response.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/examples/find_case_response.yaml
@@ -33,6 +33,7 @@ value:
           "full_name": null,
           "username": "elastic"
         },
+        "assignees": [],
         "connector": {
           "id": "none",
           "name": "none",
diff --git a/x-pack/plugins/cases/docs/openapi/components/examples/get_case_response.yaml b/x-pack/plugins/cases/docs/openapi/components/examples/get_case_response.yaml
index 936a21a5cfc70..bd74fa423bb9c 100644
--- a/x-pack/plugins/cases/docs/openapi/components/examples/get_case_response.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/examples/get_case_response.yaml
@@ -34,7 +34,9 @@ value:
     "created_at":"2022-07-13T15:33:50.604Z",
     "created_by":{"username":"elastic","email":null,"full_name":null},"status":"open",
     "updated_at":"2022-07-13T15:40:32.335Z",
-    "updated_by":{"full_name":null,"email":null,"username":"elastic"},"connector":{
+    "updated_by":{"full_name":null,"email":null,"username":"elastic"},
+    "assignees":[{"uid":"u_mGBROF_q5bmFCATbLXAcCwKa0k8JvONAwSruelyKA5E_0"}],
+    "connector":{
       "id":"none",
       "name":"none",
       "type":".none",
diff --git a/x-pack/plugins/cases/docs/openapi/components/examples/update_case_response.yaml b/x-pack/plugins/cases/docs/openapi/components/examples/update_case_response.yaml
index 7413547e6ff60..eaf421771b51e 100644
--- a/x-pack/plugins/cases/docs/openapi/components/examples/update_case_response.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/examples/update_case_response.yaml
@@ -31,6 +31,7 @@ value:
         "full_name": null,
         "username": "elastic"
       },
+      "assignees": [],
       "connector": {
         "id": "131d4448-abe0-4789-939d-8ef60680b498",
         "name": "My connector",
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/action_types.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/action_types.yaml
index 05e3fc6ab04b7..3568008b07000 100644
--- a/x-pack/plugins/cases/docs/openapi/components/schemas/action_types.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/action_types.yaml
@@ -1,6 +1,7 @@
 type: string
 description: The type of action.
 enum:
+  - assignees
   - create_case
   - comment
   - connector
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/case_response_properties.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/case_response_properties.yaml
index a53d88f3be69b..1caa1643476d5 100644
--- a/x-pack/plugins/cases/docs/openapi/components/schemas/case_response_properties.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/case_response_properties.yaml
@@ -22,7 +22,20 @@ required:
   - updated_at
   - updated_by
   - version
-properties: 
+properties:
+  assignees:
+    type: array
+    description: An array containing users that are assigned to the case.
+    nullable: true
+    items:
+      type: object
+      required:
+        - uid
+      properties:
+        uid:
+          type: string
+          description: A unique identifier for the user profile. You can use the get user profile API to retrieve more details.
+          example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
   closed_at:
     type: string
     format: date-time
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/create_case_request.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/create_case_request.yaml
index ab6b49c653668..715bfaf112042 100644
--- a/x-pack/plugins/cases/docs/openapi/components/schemas/create_case_request.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/create_case_request.yaml
@@ -10,6 +10,19 @@ required:
       - tags
       - title
 properties:
+  assignees:
+    type: array
+    description: An array containing users that are assigned to the case.
+    nullable: true
+    items:
+      type: object
+      required:
+        - uid
+      properties:
+        uid:
+          type: string
+          description: A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.
+          example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
   connector:
     oneOf:
       - $ref: 'connector_properties_none.yaml'
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/payload_assignees.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/payload_assignees.yaml
new file mode 100644
index 0000000000000..122541dfe4fe6
--- /dev/null
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/payload_assignees.yaml
@@ -0,0 +1,9 @@
+type: object
+properties:
+  assignees:
+    type: array
+    items:
+      type: object
+      properties:
+        uid:
+          type: string
\ No newline at end of file
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/update_case_request.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/update_case_request.yaml
index f6feac43b1613..ee4249aeaf9d3 100644
--- a/x-pack/plugins/cases/docs/openapi/components/schemas/update_case_request.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/update_case_request.yaml
@@ -13,7 +13,20 @@ properties:
       required:
         - id
         - version
-      properties: 
+      properties:
+        assignees:
+          type: array
+          description: An array containing users that are assigned to the case.
+          nullable: true
+          items:
+            type: object
+            required:
+             - uid
+            properties:
+              uid:
+                type: string
+                description: A unique identifier for the user profile. These identifiers can be found by using the suggest user profile API.
+                example: u_0wpfV1MqYDaXzLtRVY-gLMrddKDEmfz51Fszhj7hWC8_0
         connector:
           oneOf:
             - $ref: 'connector_properties_none.yaml'
diff --git a/x-pack/plugins/cases/docs/openapi/components/schemas/user_actions_response_properties.yaml b/x-pack/plugins/cases/docs/openapi/components/schemas/user_actions_response_properties.yaml
index e828f3441cb5d..a3f57ed53297d 100644
--- a/x-pack/plugins/cases/docs/openapi/components/schemas/user_actions_response_properties.yaml
+++ b/x-pack/plugins/cases/docs/openapi/components/schemas/user_actions_response_properties.yaml
@@ -24,6 +24,7 @@ properties:
   payload:
     oneOf:
       - $ref: 'payload_alert_comment.yaml'
+      - $ref: 'payload_assignees.yaml'
       - $ref: 'payload_connector.yaml'
       - $ref: 'payload_create_case.yaml'
       - $ref: 'payload_description.yaml'