diff --git a/dotCMS/src/main/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImpl.java b/dotCMS/src/main/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImpl.java
index 09f233bc0120..afeb560188e0 100644
--- a/dotCMS/src/main/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImpl.java
+++ b/dotCMS/src/main/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImpl.java
@@ -7671,6 +7671,10 @@ public void validateContentlet(final Contentlet contentlet, final List<Category>
             // validate unique
             if (field.isUnique()) {
                 try {
+                    if (!UtilMethods.isSet(contentlet.getHost())) {
+                        populateHost(contentlet);
+                    }
+
                     uniqueFieldValidationStrategyResolver.get().get().validate(contentlet,
                             LegacyFieldTransformer.from(field));
                 } catch (final UniqueFieldValueDuplicatedException e) {
diff --git a/dotcms-integration/src/test/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImplTest.java b/dotcms-integration/src/test/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImplTest.java
index dc9bb933b5aa..a61f64e7fd1d 100644
--- a/dotcms-integration/src/test/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImplTest.java
+++ b/dotcms-integration/src/test/java/com/dotcms/content/elasticsearch/business/ESContentletAPIImplTest.java
@@ -94,6 +94,7 @@
 import com.rainerhahnekamp.sneakythrow.Sneaky;
 import com.tngtech.java.junit.dataprovider.DataProvider;
 import com.tngtech.java.junit.dataprovider.UseDataProvider;
+import io.vavr.control.Try;
 import org.apache.http.HttpStatus;
 import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
@@ -4528,4 +4529,56 @@ public void cleanUpExtraTableAfterDeleteContentType() throws DotDataException, D
             ESContentletAPIImpl.setFeatureFlagDbUniqueFieldValidation(oldEnabledDataBaseValidation);
         }
     }
+
+    /**
+     * Method to test: {@link ContentletAPI#checkin(Contentlet, User, boolean)}  }
+     * When: try to save a {@link Contentlet} that don't have the Host set already
+     * Should: populate the Host for the {@link Contentlet} (in this case using the {@link ContentType}'s Host)
+     * and save the siteId in the supporting_values Json field in the unique_fields table
+     *
+     * @throws DotDataException
+     * @throws DotSecurityException
+     */
+    @Test
+    public void saveSiteIDRightInSupportingValues() throws DotDataException, DotSecurityException {
+        final boolean oldEnabledDataBaseValidation = ESContentletAPIImpl.getFeatureFlagDbUniqueFieldValidation();
+
+        try {
+            ESContentletAPIImpl.setFeatureFlagDbUniqueFieldValidation(true);
+            final Host host = new SiteDataGen().nextPersisted();
+
+            final ContentType contentType = new ContentTypeDataGen()
+                    .host(host)
+                    .nextPersisted();
+
+            final Language language = new LanguageDataGen().nextPersisted();
+
+            final Field uniqueTextField = new FieldDataGen()
+                    .contentTypeId(contentType.id())
+                    .unique(true)
+                    .type(TextField.class)
+                    .nextPersisted();
+
+            final Contentlet contentlet = new Contentlet();
+            contentlet.setLanguageId(language.getId());
+            contentlet.setBoolProperty(Contentlet.IS_TEST_MODE, true);
+            contentlet.setContentTypeId(Try.of(()->APILocator.getContentTypeAPI(APILocator.systemUser())
+                    .find(contentType.id()).id()).getOrNull());
+            contentlet.setProperty(uniqueTextField.variable(), "unique-value");
+
+            contentlet.setIndexPolicy(IndexPolicy.FORCE);
+            contentlet.setBoolProperty(Contentlet.DISABLE_WORKFLOW, true);
+            contentletAPI.checkin(contentlet, user, false);
+
+            final List<Map<String, Object>> results = new DotConnect().setSQL("SELECT * FROM unique_fields WHERE supporting_values->>'" + CONTENT_TYPE_ID_ATTR + "' = ?")
+                    .addParam(contentType.id())
+                    .loadObjectResults();
+            assertEquals(1, results.size());
+
+            final Map<String, Object> supportingValue = getSupportingValue(results.get(0));
+            assertEquals(host.getIdentifier(), supportingValue.get(SITE_ID_ATTR));
+        } finally {
+            ESContentletAPIImpl.setFeatureFlagDbUniqueFieldValidation(oldEnabledDataBaseValidation);
+        }
+    }
 }