diff --git a/docs/development/core/server/kibana-plugin-core-server.legacyclusterclient.callasinternaluser.md b/docs/development/core/server/kibana-plugin-core-server.legacyclusterclient.callasinternaluser.md
index 2e235485711c6..7c8cc18d24e29 100644
--- a/docs/development/core/server/kibana-plugin-core-server.legacyclusterclient.callasinternaluser.md
+++ b/docs/development/core/server/kibana-plugin-core-server.legacyclusterclient.callasinternaluser.md
@@ -4,6 +4,11 @@
 
 ## LegacyClusterClient.callAsInternalUser property
 
+> Warning: This API is now obsolete.
+> 
+> Use [IClusterClient.asInternalUser](./kibana-plugin-core-server.iclusterclient.asinternaluser.md)<!-- -->.
+> 
+
 Calls specified endpoint with provided clientParams on behalf of the Kibana internal user. See [LegacyAPICaller](./kibana-plugin-core-server.legacyapicaller.md)<!-- -->.
 
 <b>Signature:</b>
diff --git a/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callascurrentuser.md b/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callascurrentuser.md
index 9130f9adde76e..7517acc59ac80 100644
--- a/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callascurrentuser.md
+++ b/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callascurrentuser.md
@@ -4,6 +4,11 @@
 
 ## LegacyScopedClusterClient.callAsCurrentUser() method
 
+> Warning: This API is now obsolete.
+> 
+> Use [IScopedClusterClient.asCurrentUser](./kibana-plugin-core-server.iscopedclusterclient.ascurrentuser.md)<!-- -->.
+> 
+
 Calls specified `endpoint` with provided `clientParams` on behalf of the user initiated request to the Kibana server (via HTTP request headers). See [LegacyAPICaller](./kibana-plugin-core-server.legacyapicaller.md)<!-- -->.
 
 <b>Signature:</b>
diff --git a/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callasinternaluser.md b/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callasinternaluser.md
index bf95782299e72..b683d3945f9ff 100644
--- a/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callasinternaluser.md
+++ b/docs/development/core/server/kibana-plugin-core-server.legacyscopedclusterclient.callasinternaluser.md
@@ -4,6 +4,11 @@
 
 ## LegacyScopedClusterClient.callAsInternalUser() method
 
+> Warning: This API is now obsolete.
+> 
+> Use [IScopedClusterClient.asInternalUser](./kibana-plugin-core-server.iscopedclusterclient.asinternaluser.md)<!-- -->.
+> 
+
 Calls specified `endpoint` with provided `clientParams` on behalf of the Kibana internal user. See [LegacyAPICaller](./kibana-plugin-core-server.legacyapicaller.md)<!-- -->.
 
 <b>Signature:</b>
diff --git a/src/core/server/elasticsearch/legacy/cluster_client.ts b/src/core/server/elasticsearch/legacy/cluster_client.ts
index 00417e3bef4f4..e851b3a4db711 100644
--- a/src/core/server/elasticsearch/legacy/cluster_client.ts
+++ b/src/core/server/elasticsearch/legacy/cluster_client.ts
@@ -140,6 +140,7 @@ export class LegacyClusterClient implements ILegacyClusterClient {
    * Calls specified endpoint with provided clientParams on behalf of the
    * Kibana internal user.
    * See {@link LegacyAPICaller}.
+   * @deprecated Use {@link IClusterClient.asInternalUser}.
    *
    * @param endpoint - String descriptor of the endpoint e.g. `cluster.getSettings` or `ping`.
    * @param clientParams - A dictionary of parameters that will be passed directly to the Elasticsearch JS client.
diff --git a/src/core/server/elasticsearch/legacy/scoped_cluster_client.ts b/src/core/server/elasticsearch/legacy/scoped_cluster_client.ts
index 65484f0927c9e..e3f3d33d03766 100644
--- a/src/core/server/elasticsearch/legacy/scoped_cluster_client.ts
+++ b/src/core/server/elasticsearch/legacy/scoped_cluster_client.ts
@@ -56,6 +56,7 @@ export class LegacyScopedClusterClient implements ILegacyScopedClusterClient {
    * Calls specified `endpoint` with provided `clientParams` on behalf of the
    * Kibana internal user.
    * See {@link LegacyAPICaller}.
+   * @deprecated Use {@link IScopedClusterClient.asInternalUser}.
    *
    * @param endpoint - String descriptor of the endpoint e.g. `cluster.getSettings` or `ping`.
    * @param clientParams - A dictionary of parameters that will be passed directly to the Elasticsearch JS client.
@@ -73,6 +74,7 @@ export class LegacyScopedClusterClient implements ILegacyScopedClusterClient {
    * Calls specified `endpoint` with provided `clientParams` on behalf of the
    * user initiated request to the Kibana server (via HTTP request headers).
    * See {@link LegacyAPICaller}.
+   * @deprecated Use {@link IScopedClusterClient.asCurrentUser}.
    *
    * @param endpoint - String descriptor of the endpoint e.g. `cluster.getSettings` or `ping`.
    * @param clientParams - A dictionary of parameters that will be passed directly to the Elasticsearch JS client.
diff --git a/src/core/server/index.ts b/src/core/server/index.ts
index 7b19c3a686757..9e654ea1e2303 100644
--- a/src/core/server/index.ts
+++ b/src/core/server/index.ts
@@ -394,6 +394,9 @@ export interface RequestHandlerContext {
     elasticsearch: {
       client: IScopedClusterClient;
       legacy: {
+        /*
+         * @deprecated Use {@link IScopedClusterClient}.
+         */
         client: ILegacyScopedClusterClient;
       };
     };
diff --git a/src/core/server/server.api.md b/src/core/server/server.api.md
index a03e5ec9acd27..8dddff07a0e4c 100644
--- a/src/core/server/server.api.md
+++ b/src/core/server/server.api.md
@@ -1324,6 +1324,7 @@ export interface LegacyCallAPIOptions {
 export class LegacyClusterClient implements ILegacyClusterClient {
     constructor(config: LegacyElasticsearchClientConfig, log: Logger, getAuthHeaders?: GetAuthHeaders);
     asScoped(request?: ScopeableRequest): ILegacyScopedClusterClient;
+    // @deprecated
     callAsInternalUser: LegacyAPICaller;
     close(): void;
     }
@@ -1371,7 +1372,9 @@ export interface LegacyRequest extends Request {
 // @public @deprecated
 export class LegacyScopedClusterClient implements ILegacyScopedClusterClient {
     constructor(internalAPICaller: LegacyAPICaller, scopedAPICaller: LegacyAPICaller, headers?: Headers | undefined);
+    // @deprecated
     callAsCurrentUser(endpoint: string, clientParams?: Record<string, any>, options?: LegacyCallAPIOptions): Promise<any>;
+    // @deprecated
     callAsInternalUser(endpoint: string, clientParams?: Record<string, any>, options?: LegacyCallAPIOptions): Promise<any>;
     }