diff --git a/gems/aws-sdk-core/CHANGELOG.md b/gems/aws-sdk-core/CHANGELOG.md
index 44e95976791..2bf6e4d9181 100644
--- a/gems/aws-sdk-core/CHANGELOG.md
+++ b/gems/aws-sdk-core/CHANGELOG.md
@@ -1,6 +1,8 @@
 Unreleased Changes
 ------------------
 
+* Issue - Ensure `SSOCredentials` `#expiration` is a `Time` (#2874)
+
 3.176.0 (2023-06-28)
 ------------------
 
diff --git a/gems/aws-sdk-core/lib/aws-sdk-core/sso_credentials.rb b/gems/aws-sdk-core/lib/aws-sdk-core/sso_credentials.rb
index 8557a84dbe2..5613d357470 100644
--- a/gems/aws-sdk-core/lib/aws-sdk-core/sso_credentials.rb
+++ b/gems/aws-sdk-core/lib/aws-sdk-core/sso_credentials.rb
@@ -158,7 +158,7 @@ def refresh
         c.secret_access_key,
         c.session_token
       )
-      @expiration = c.expiration
+      @expiration = Time.at(c.expiration / 1000.0)
     end
 
     def sso_cache_file
diff --git a/gems/aws-sdk-core/spec/aws/sso_credentials_spec.rb b/gems/aws-sdk-core/spec/aws/sso_credentials_spec.rb
index 1f1d8b438da..0ebd50cf557 100644
--- a/gems/aws-sdk-core/spec/aws/sso_credentials_spec.rb
+++ b/gems/aws-sdk-core/spec/aws/sso_credentials_spec.rb
@@ -12,17 +12,18 @@ module Aws
       )
     end
 
-    let(:in_one_hour) { Time.now + 60 * 60 }
-    let(:one_hour_ago) { Time.now - 60 * 60 }
+    let(:time) { Time.at(Time.now.to_i) }
+    let(:in_one_hour) { time + 60 * 60 }
+    let(:one_hour_ago) { time - 60 * 60 }
     let(:expiration) { in_one_hour }
 
     let(:sso_resp) do
       {
         role_credentials: {
-        access_key_id: 'akid',
-        secret_access_key: 'secret',
-        session_token: 'session',
-        expiration: expiration.to_i
+          access_key_id: 'akid',
+          secret_access_key: 'secret',
+          session_token: 'session',
+          expiration: expiration.to_i * 1000
         }
       }
     end
@@ -135,6 +136,14 @@ def mock_token_file(start_url, cached_token)
           sso_creds.credentials
         end
       end
+
+      describe '#expiration' do
+        it 'parses expiration as Time' do
+          sso_creds = SSOCredentials.new(sso_opts)
+          expect(sso_creds.expiration).to be_a(Time)
+          expect(sso_creds.expiration).to eq(expiration)
+        end
+      end
     end
 
     context 'legacy profile' do