diff --git a/src/main/java/com/knecon/fforesight/tenantusermanagement/api/external/TenantsResource.java b/src/main/java/com/knecon/fforesight/tenantusermanagement/api/external/TenantsResource.java
index 0e528fd..7921e66 100644
--- a/src/main/java/com/knecon/fforesight/tenantusermanagement/api/external/TenantsResource.java
+++ b/src/main/java/com/knecon/fforesight/tenantusermanagement/api/external/TenantsResource.java
@@ -60,4 +60,9 @@ public interface TenantsResource {
     @ApiResponses(value = {@ApiResponse(responseCode = "200", description = "OK")})
     DeploymentKeyResponse getDeploymentKey(@PathVariable(TENANT_ID_PARAM) String tenantId);
 
+    @PostMapping(value = "/tenants/{tenantId}/appPrefix", consumes = MediaType.APPLICATION_JSON_VALUE)
+    @Operation(summary = "Set custom app prefix for existing tenant", description = "None")
+    @ApiResponses(value = {@ApiResponse(responseCode = "200", description = "OK")})
+    void updateAppPrefix(@PathVariable("tenantId") String tenantId, @RequestBody String appPrefix);
+
 }
diff --git a/src/main/java/com/knecon/fforesight/tenantusermanagement/api/internal/InternalTenantsResource.java b/src/main/java/com/knecon/fforesight/tenantusermanagement/api/internal/InternalTenantsResource.java
index 6604bda..566e555 100644
--- a/src/main/java/com/knecon/fforesight/tenantusermanagement/api/internal/InternalTenantsResource.java
+++ b/src/main/java/com/knecon/fforesight/tenantusermanagement/api/internal/InternalTenantsResource.java
@@ -68,4 +68,10 @@ public interface InternalTenantsResource {
     @ApiResponses(value = {@ApiResponse(responseCode = "200", description = "OK")})
     DeploymentKeyResponse getDeploymentKey(@PathVariable(TENANT_ID_PARAM) String tenantId);
 
+
+    @PostMapping(value = "/tenants/{tenantId}/appPrefix", consumes = MediaType.APPLICATION_JSON_VALUE)
+    @Operation(summary = "Set custom app prefix for existing tenant", description = "None")
+    @ApiResponses(value = {@ApiResponse(responseCode = "200", description = "OK")})
+    void updateAppPrefix(@PathVariable("tenantId") String tenantId, @RequestBody String appPrefix);
+
 }
diff --git a/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/external/TenantsController.java b/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/external/TenantsController.java
index 904f9da..ca8a2c2 100644
--- a/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/external/TenantsController.java
+++ b/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/external/TenantsController.java
@@ -81,4 +81,13 @@ public class TenantsController implements TenantsResource, PublicResource {
         return new DeploymentKeyResponse(deploymentKeyService.getDeploymentKey(tenantId));
     }
 
+
+    @PreAuthorize("hasAuthority('" + UPDATE_TENANT + "')")
+    public void updateAppPrefix(@PathVariable(TENANT_ID_PARAM) String tenantId,
+                                       @RequestBody String appPrefix) {
+
+        tenantManagementService.updateAppPrefix(tenantId, appPrefix);
+
+    }
+
 }
diff --git a/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/internal/InternalTenantsController.java b/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/internal/InternalTenantsController.java
index 123fb38..1054470 100644
--- a/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/internal/InternalTenantsController.java
+++ b/src/main/java/com/knecon/fforesight/tenantusermanagement/controller/internal/InternalTenantsController.java
@@ -1,8 +1,11 @@
 package com.knecon.fforesight.tenantusermanagement.controller.internal;
 
+import static com.knecon.fforesight.tenantusermanagement.permissions.UserManagementPermissions.UPDATE_TENANT;
+
 import java.util.List;
 
 import org.springframework.http.HttpStatus;
+import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RestController;
@@ -76,4 +79,11 @@ public class InternalTenantsController implements InternalTenantsResource, Inter
         return new DeploymentKeyResponse(deploymentKeyService.getDeploymentKey(tenantId));
     }
 
+
+    public void updateAppPrefix(@PathVariable(TENANT_ID_PARAM) String tenantId,
+                                @RequestBody String appPrefix) {
+
+        tenantManagementService.updateAppPrefix(tenantId, appPrefix);
+
+    }
 }
diff --git a/src/main/java/com/knecon/fforesight/tenantusermanagement/service/TenantManagementService.java b/src/main/java/com/knecon/fforesight/tenantusermanagement/service/TenantManagementService.java
index 9f595a4..77cfc62 100644
--- a/src/main/java/com/knecon/fforesight/tenantusermanagement/service/TenantManagementService.java
+++ b/src/main/java/com/knecon/fforesight/tenantusermanagement/service/TenantManagementService.java
@@ -178,7 +178,13 @@ public class TenantManagementService implements TenantProvider {
 
     private String buildIndexPrefix(String tenantId) {
 
-        return tenantUserManagementProperties.getAppPrefix() + "_" + tenantId;
+        return buildIndexPrefix(tenantId, tenantUserManagementProperties.getAppPrefix());
+    }
+
+
+    private String buildIndexPrefix(String tenantId, String appPrefix) {
+
+        return appPrefix + "_" + tenantId;
     }
 
 
@@ -581,4 +587,20 @@ public class TenantManagementService implements TenantProvider {
         realmService.realm(MASTER_REALM).update(realmRepresentation);
     }
 
+
+    public void updateAppPrefix(String tenantId, String appPrefix) {
+
+        if (appPrefix == null || appPrefix.isEmpty()) {
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "App prefix cannot be empty.");
+        }
+
+        var tenant = tenantRepository.findById(tenantId);
+        if (tenant.isPresent()) {
+            tenantUserManagementProperties.setAppPrefix(buildIndexPrefix(tenantId, appPrefix));
+        } else {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Tenant does not exist");
+        }
+
+    }
+
 }