diff --git a/src-docs/src/views/i18n/i18n_interpolation.js b/src-docs/src/views/i18n/i18n_interpolation.js
index 4c830cc37c5..1e5c90dfdf8 100644
--- a/src-docs/src/views/i18n/i18n_interpolation.js
+++ b/src-docs/src/views/i18n/i18n_interpolation.js
@@ -10,7 +10,7 @@ import {
 } from '../../../../src/components';
 
 export default () => {
-  const [count, setCount] = useState(1);
+  const [count, setCount] = useState(0);
 
   return (
     <>
@@ -44,6 +44,35 @@ export default () => {
 
       <EuiSpacer size="l" />
 
+      <EuiTitle size="xs">
+        <h3>useEuiI18n with function interpolation</h3>
+      </EuiTitle>
+      <p>
+        {useEuiI18n(
+          'euiI18nInterpolation.clickedCount',
+          ({ count }) =>
+            `Clicked on button ${count} time${count === 1 ? '' : 's'}.`,
+          { count }
+        )}
+      </p>
+
+      <EuiSpacer size="l" />
+
+      <EuiTitle size="xs">
+        <h3>EuiI18n with function interpolation</h3>
+      </EuiTitle>
+      <p>
+        <EuiI18n
+          token="euiI18nInterpolation.clickedCount"
+          default={({ count }) =>
+            `Clicked on button ${count} time${count === 1 ? '' : 's'}.`
+          }
+          values={{ count }}
+        />
+      </p>
+
+      <EuiSpacer size="l" />
+
       <EuiTitle size="xs">
         <h3>useEuiI18n with component interpolation</h3>
       </EuiTitle>
diff --git a/src/components/i18n/__snapshots__/i18n.test.tsx.snap b/src/components/i18n/__snapshots__/i18n.test.tsx.snap
index cd57a4145d1..45c85c487b7 100644
--- a/src/components/i18n/__snapshots__/i18n.test.tsx.snap
+++ b/src/components/i18n/__snapshots__/i18n.test.tsx.snap
@@ -249,7 +249,19 @@ exports[`EuiI18n mapped tokens mappingFunc calls the mapping function with the s
       "mapping": Object {
         "test1": "This is the mapped value.",
       },
-      "mappingFunc": [Function],
+      "mappingFunc": [MockFunction] {
+        "calls": Array [
+          Array [
+            "placeholder",
+          ],
+        ],
+        "results": Array [
+          Object {
+            "type": "return",
+            "value": "PLACEHOLDER",
+          },
+        ],
+      },
     }
   }
 >
@@ -270,7 +282,19 @@ exports[`EuiI18n reading values from context mappingFunc calls the mapping funct
       "mapping": Object {
         "test1": "This is the mapped value.",
       },
-      "mappingFunc": [Function],
+      "mappingFunc": [MockFunction] {
+        "calls": Array [
+          Array [
+            "This is the basic string.",
+          ],
+        ],
+        "results": Array [
+          Object {
+            "type": "return",
+            "value": "THIS IS THE BASIC STRING.",
+          },
+        ],
+      },
     }
   }
 >
@@ -321,6 +345,60 @@ exports[`EuiI18n reading values from context render prop with multiple tokens re
 </EuiContext>
 `;
 
+exports[`EuiI18n reading values from context render prop with multiple tokens uses the mapping function if one is provided 1`] = `
+<EuiContext
+  i18n={
+    Object {
+      "mapping": Object {
+        "test1": "This is the first mapped value.",
+        "test2": "This is the second mapped value.",
+      },
+      "mappingFunc": [MockFunction] {
+        "calls": Array [
+          Array [
+            "This is the first basic string.",
+          ],
+          Array [
+            "This is the second basic string.",
+          ],
+        ],
+        "results": Array [
+          Object {
+            "type": "return",
+            "value": "THIS IS THE FIRST BASIC STRING.",
+          },
+          Object {
+            "type": "return",
+            "value": "THIS IS THE SECOND BASIC STRING.",
+          },
+        ],
+      },
+    }
+  }
+>
+  <EuiI18n
+    defaults={
+      Array [
+        "This is the first basic string.",
+        "This is the second basic string.",
+      ]
+    }
+    tokens={
+      Array [
+        "test1",
+        "test2",
+      ]
+    }
+  >
+    <div>
+      THIS IS THE FIRST BASIC STRING.
+       
+      THIS IS THE SECOND BASIC STRING.
+    </div>
+  </EuiI18n>
+</EuiContext>
+`;
+
 exports[`EuiI18n reading values from context render prop with single token calls a mapped function and renders render prop result to the dom 1`] = `
 <EuiContext
   i18n={
@@ -506,7 +584,7 @@ exports[`EuiI18n reading values from context rendering to dom renders a mapped s
 </EuiContext>
 `;
 
-exports[`EuiI18n useEuiI18n unmapped calls a function and renders the result to the dom 1`] = `
+exports[`EuiI18n useEuiI18n unmapped calls a function that returns JSX and renders the result to the dom 1`] = `
 <Component>
   <div>
     <p>
@@ -520,6 +598,34 @@ exports[`EuiI18n useEuiI18n unmapped calls a function and renders the result to
 </Component>
 `;
 
+exports[`EuiI18n useEuiI18n unmapped calls a function that returns a string and the i18n mapping function 1`] = `
+<EuiContext
+  i18n={
+    Object {
+      "mappingFunc": [MockFunction] {
+        "calls": Array [
+          Array [
+            "This is a callback with values",
+          ],
+        ],
+        "results": Array [
+          Object {
+            "type": "return",
+            "value": "THIS IS A CALLBACK WITH VALUES",
+          },
+        ],
+      },
+    }
+  }
+>
+  <Component>
+    <div>
+      THIS IS A CALLBACK WITH VALUES
+    </div>
+  </Component>
+</EuiContext>
+`;
+
 exports[`EuiI18n useEuiI18n unmapped handles multiple tokens 1`] = `
 <Component>
   <p>
diff --git a/src/components/i18n/i18n.test.tsx b/src/components/i18n/i18n.test.tsx
index 0dd25fc9723..42261c38fe7 100644
--- a/src/components/i18n/i18n.test.tsx
+++ b/src/components/i18n/i18n.test.tsx
@@ -14,6 +14,10 @@ import { EuiI18n, useEuiI18n } from './i18n';
 /* eslint-disable local/i18n */
 
 describe('EuiI18n', () => {
+  const mockMappingFunc = jest.fn((string: string) => string.toUpperCase());
+
+  beforeEach(() => jest.clearAllMocks());
+
   describe('default rendering', () => {
     describe('rendering to dom', () => {
       it('renders a basic string to the dom', () => {
@@ -210,32 +214,48 @@ describe('EuiI18n', () => {
     });
 
     describe('render prop with multiple tokens', () => {
+      const multipleTokens = (
+        <EuiI18n
+          tokens={['test1', 'test2']}
+          defaults={[
+            'This is the first basic string.',
+            'This is the second basic string.',
+          ]}
+        >
+          {([one, two]: ReactChild[]) => (
+            <div>
+              {one} {two}
+            </div>
+          )}
+        </EuiI18n>
+      );
+      const multipleTokensMapping = {
+        test1: 'This is the first mapped value.',
+        test2: 'This is the second mapped value.',
+      };
+
       it('renders mapped render prop result to the dom', () => {
+        const component = mount(
+          <EuiContext i18n={{ mapping: multipleTokensMapping }}>
+            {multipleTokens}
+          </EuiContext>
+        );
+        expect(component).toMatchSnapshot();
+      });
+
+      it('uses the mapping function if one is provided', () => {
         const component = mount(
           <EuiContext
             i18n={{
-              mapping: {
-                test1: 'This is the first mapped value.',
-                test2: 'This is the second mapped value.',
-              },
+              mapping: multipleTokensMapping,
+              mappingFunc: mockMappingFunc,
             }}
           >
-            <EuiI18n
-              tokens={['test1', 'test2']}
-              defaults={[
-                'This is the first basic string.',
-                'This is the second basic string.',
-              ]}
-            >
-              {([one, two]: ReactChild[]) => (
-                <div>
-                  {one} {two}
-                </div>
-              )}
-            </EuiI18n>
+            {multipleTokens}
           </EuiContext>
         );
         expect(component).toMatchSnapshot();
+        expect(mockMappingFunc).toHaveBeenCalledTimes(2);
       });
     });
 
@@ -247,7 +267,7 @@ describe('EuiI18n', () => {
               mapping: {
                 test1: 'This is the mapped value.',
               },
-              mappingFunc: (value: string) => value.toUpperCase(),
+              mappingFunc: mockMappingFunc,
             }}
           >
             <EuiI18n token="test1" default="This is the basic string.">
@@ -256,6 +276,7 @@ describe('EuiI18n', () => {
           </EuiContext>
         );
         expect(component).toMatchSnapshot();
+        expect(mockMappingFunc).toHaveBeenCalledTimes(1);
       });
     });
   });
@@ -300,7 +321,7 @@ describe('EuiI18n', () => {
         expect(component).toMatchSnapshot();
       });
 
-      it('calls a function and renders the result to the dom', () => {
+      it('calls a function that returns JSX and renders the result to the dom', () => {
         const values = { type: 'callback', special: 'values' };
         const renderCallback = jest.fn(({ type, special }) => (
           <p>
@@ -315,6 +336,26 @@ describe('EuiI18n', () => {
 
         expect(renderCallback).toHaveBeenCalledWith(values);
       });
+
+      it('calls a function that returns a string and the i18n mapping function', () => {
+        const values = { type: 'callback', special: 'values' };
+        const renderCallback = jest.fn(
+          ({ type, special }) => `This is a ${type} with ${special}`
+        );
+        const Component = () => (
+          <div>{useEuiI18n('test', renderCallback, values)}</div>
+        );
+
+        const component = mount(
+          <EuiContext i18n={{ mappingFunc: mockMappingFunc }}>
+            <Component />
+          </EuiContext>
+        );
+
+        expect(component).toMatchSnapshot();
+        expect(renderCallback).toHaveBeenCalledWith(values);
+        expect(mockMappingFunc).toHaveBeenCalledTimes(1);
+      });
     });
   });
 
@@ -400,7 +441,7 @@ describe('EuiI18n', () => {
               mapping: {
                 test1: 'This is the mapped value.',
               },
-              mappingFunc: (value: string) => value.toUpperCase(),
+              mappingFunc: mockMappingFunc,
             }}
           >
             <Component />
diff --git a/src/components/i18n/i18n.tsx b/src/components/i18n/i18n.tsx
index b8c9a82e4f0..7a1ad5ad041 100644
--- a/src/components/i18n/i18n.tsx
+++ b/src/components/i18n/i18n.tsx
@@ -61,7 +61,10 @@ function lookupToken<
       return errorOnMissingValues(token);
     }
     // @ts-ignore TypeScript complains that `DEFAULT` doesn't have a call signature but we verified `renderable` is a function
-    return renderable(values);
+    const rendered = renderable(values);
+    return (i18nMappingFunc && typeof rendered === 'string'
+      ? i18nMappingFunc(rendered)
+      : rendered) as RESOLVED;
   } else if (values === undefined || typeof renderable !== 'string') {
     if (i18nMappingFunc && typeof valueDefault === 'string') {
       renderable = i18nMappingFunc(valueDefault);
@@ -133,6 +136,7 @@ const EuiI18n = <
             lookupToken({
               token,
               i18nMapping: mapping,
+              i18nMappingFunc: mappingFunc,
               valueDefault: props.defaults[idx],
               render,
             })
diff --git a/upcoming_changelogs/5748.md b/upcoming_changelogs/5748.md
new file mode 100644
index 00000000000..e0917664c2c
--- /dev/null
+++ b/upcoming_changelogs/5748.md
@@ -0,0 +1,3 @@
+**Bug fixes**
+
+- Fixed `EuiContext.i18n`'s `mappingFunc` not being called for `EuiI18n`s with multiple tokens or function callbacks