diff --git a/test/api_integration/services/supertest.ts b/test/api_integration/services/supertest.ts
index 1257a934da8be..a0268b78cb151 100644
--- a/test/api_integration/services/supertest.ts
+++ b/test/api_integration/services/supertest.ts
@@ -19,6 +19,14 @@ export function KibanaSupertestProvider({ getService }: FtrProviderContext) {
 
 export function ElasticsearchSupertestProvider({ getService }: FtrProviderContext) {
   const config = getService('config');
-  const elasticSearchServerUrl = formatUrl(config.get('servers.elasticsearch'));
-  return supertestAsPromised(elasticSearchServerUrl);
+  const esServerConfig = config.get('servers.elasticsearch');
+  const elasticSearchServerUrl = formatUrl(esServerConfig);
+
+  let agentOptions = {};
+  if ('certificateAuthorities' in esServerConfig) {
+    agentOptions = { ca: esServerConfig!.certificateAuthorities };
+  }
+
+  // @ts-ignore - supertestAsPromised doesn't like the agentOptions, but still passes it correctly to supertest
+  return supertestAsPromised.agent(elasticSearchServerUrl, agentOptions);
 }
diff --git a/x-pack/test/functional_with_es_ssl/config.ts b/x-pack/test/functional_with_es_ssl/config.ts
index 5be8eee3155b9..a7259f2410d6b 100644
--- a/x-pack/test/functional_with_es_ssl/config.ts
+++ b/x-pack/test/functional_with_es_ssl/config.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import Fs from 'fs';
 import { resolve, join } from 'path';
 import { CA_CERT_PATH } from '@kbn/dev-utils';
 import { FtrConfigProviderContext } from '@kbn/test/types/ftr';
@@ -33,6 +34,7 @@ export default async function ({ readConfigFile }: FtrConfigProviderContext) {
     elasticsearch: {
       ...xpackFunctionalConfig.get('servers.elasticsearch'),
       protocol: 'https',
+      certificateAuthorities: [Fs.readFileSync(CA_CERT_PATH)],
     },
   };