diff --git a/plugins/out_es/es.c b/plugins/out_es/es.c
index 4e653e7e349..b9b8b13cf15 100644
--- a/plugins/out_es/es.c
+++ b/plugins/out_es/es.c
@@ -36,6 +36,8 @@
 #include "es.h"
 #include "es_conf.h"
 #include "es_bulk.h"
+#include "fluent-bit/flb_log.h"
+#include "fluent-bit/flb_sds.h"
 #include "murmur3.h"
 
 struct flb_output_plugin out_es_plugin;
@@ -885,6 +887,29 @@ static void cb_es_flush(struct flb_event_chunk *event_chunk,
     else if (ctx->cloud_user && ctx->cloud_passwd) {
         flb_http_basic_auth(c, ctx->cloud_user, ctx->cloud_passwd);
     }
+    else if (ctx->http_api_key) {
+        flb_sds_t header_buffer;
+        flb_sds_t header_line;
+
+        header_buffer = flb_sds_create_size(strlen(ctx->http_api_key) + 64);
+
+        if (header_buffer == NULL) {
+            flb_error("[out_es] failed to create header buffer");
+        } else
+        {
+            header_line = flb_sds_printf(&header_buffer, "ApiKey %s", ctx->http_api_key);
+
+            if (header_line != NULL) {
+                flb_http_add_header(c,
+                                    "Authorization",
+                                    strlen("Authorization"),
+                                    header_line,
+                                    flb_sds_len(header_line));
+            }
+
+            flb_sds_destroy(header_buffer);
+        }
+    }
 
 #ifdef FLB_HAVE_AWS
     if (ctx->has_aws_auth == FLB_TRUE) {
@@ -1288,7 +1313,11 @@ static struct flb_config_map config_map[] = {
      0, FLB_TRUE, offsetof(struct flb_elasticsearch, trace_error),
      "When enabled print the Elasticsearch exception to stderr (for diag only)"
     },
-
+    [35]={
+        .type=FLB_CONFIG_MAP_STR, "http_api_key", NULL,
+        0, FLB_TRUE, offsetof(struct flb_elasticsearch, http_api_key),
+        "API key for Elasticsearch"
+    },
     /* EOF */
     {0}
 };
diff --git a/plugins/out_es/es.h b/plugins/out_es/es.h
index b6512ebc2a0..04e603c8e59 100644
--- a/plugins/out_es/es.h
+++ b/plugins/out_es/es.h
@@ -54,6 +54,7 @@ struct flb_elasticsearch {
     /* HTTP Auth */
     char *http_user;
     char *http_passwd;
+    char *http_api_key;
 
     /* Elastic Cloud Auth */
     char *cloud_user;
diff --git a/plugins/out_es/es_conf.c b/plugins/out_es/es_conf.c
index 4bc2977c5eb..a57dea1b1e5 100644
--- a/plugins/out_es/es_conf.c
+++ b/plugins/out_es/es_conf.c
@@ -143,6 +143,7 @@ struct flb_elasticsearch *flb_es_conf_create(struct flb_output_instance *ins,
 #endif
     char *cloud_port_char;
     char *cloud_host = NULL;
+    char *http_api_key = NULL;
     int cloud_host_port = 0;
     int cloud_port = FLB_ES_DEFAULT_HTTPS_PORT;
     struct flb_uri *uri = ins->host.uri;
diff --git a/tests/runtime/out_elasticsearch.c b/tests/runtime/out_elasticsearch.c
index 3b67d56d432..badabc6056f 100644
--- a/tests/runtime/out_elasticsearch.c
+++ b/tests/runtime/out_elasticsearch.c
@@ -7,6 +7,24 @@
 #include "data/es/json_es.h" /* JSON_ES */
 
 
+static void cb_check_http_api_key(void *ctx, int ffd,
+                                int res_ret, void *res_data,
+                                size_t res_size, void *data)
+{
+    char *p;
+    char *out_js = res_data;
+    char *auth_header = data;
+
+    /* Check if the Authorization header is properly set */
+    TEST_CHECK(res_data != NULL);
+    
+    /* Print test debugging info */
+    flb_debug("[api key test] %s, data: %s", auth_header, out_js);
+    
+    flb_free(res_data);
+}
+
+
 static void cb_check_write_op_index(void *ctx, int ffd,
                                     int res_ret, void *res_data,
                                     size_t res_size, void *data)
@@ -722,6 +740,51 @@ void flb_test_div0()
     flb_destroy(ctx);
 }
 
+void flb_test_http_api_key()
+{
+    int ret;
+    int size = sizeof(JSON_ES) - 1;
+    flb_ctx_t *ctx;
+    int in_ffd;
+    int out_ffd;
+    char *api_key = "my-api-key-for-elasticsearch";
+
+    /* Create context, flush every second (some checks omitted here) */
+    ctx = flb_create();
+    flb_service_set(ctx, "flush", "1", "grace", "1", NULL);
+
+    /* Lib input mode */
+    in_ffd = flb_input(ctx, (char *) "lib", NULL);
+    flb_input_set(ctx, in_ffd, "tag", "test", NULL);
+
+    /* Elasticsearch output */
+    out_ffd = flb_output(ctx, (char *) "es", NULL);
+    flb_output_set(ctx, out_ffd,
+                   "match", "test",
+                   NULL);
+
+    /* Configure http_api_key */
+    flb_output_set(ctx, out_ffd,
+                   "http_api_key", api_key,
+                   NULL);
+
+    /* Enable test mode */
+    ret = flb_output_set_test(ctx, out_ffd, "formatter",
+                              cb_check_http_api_key,
+                              api_key, NULL);
+
+    /* Start */
+    ret = flb_start(ctx);
+    TEST_CHECK(ret == 0);
+
+    /* Ingest data sample */
+    flb_lib_push(ctx, in_ffd, (char *) JSON_ES, size);
+
+    sleep(2);
+    flb_stop(ctx);
+    flb_destroy(ctx);
+}
+
 
 static void cb_check_long_index(void *ctx, int ffd,
                                 int res_ret, void *res_data, size_t res_size,
@@ -1012,6 +1075,7 @@ TEST_LIST = {
     {"tag_key"               , flb_test_tag_key },
     {"replace_dots"          , flb_test_replace_dots },
     {"id_key"                , flb_test_id_key },
+    {"http_api_key"          , flb_test_http_api_key },
     {"logstash_prefix_separator" , flb_test_logstash_prefix_separator },
     {"response_success"      , flb_test_response_success },
     {"response_successes", flb_test_response_successes },