diff --git a/direct-query-core/src/main/java/org/opensearch/sql/prometheus/client/PrometheusClientImpl.java b/direct-query-core/src/main/java/org/opensearch/sql/prometheus/client/PrometheusClientImpl.java
index c6594bec278..d5dffa02391 100644
--- a/direct-query-core/src/main/java/org/opensearch/sql/prometheus/client/PrometheusClientImpl.java
+++ b/direct-query-core/src/main/java/org/opensearch/sql/prometheus/client/PrometheusClientImpl.java
@@ -115,6 +115,9 @@ public JSONObject queryRange(
     logger.debug("Received Prometheus response for query_range: code={}", response);
 
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new JSONObject();
+    }
     return jsonObject.getJSONObject("data");
   }
 
@@ -149,6 +152,9 @@ public JSONObject query(String query, Long time, Integer limit, Integer timeout)
 
     logger.info("Received Prometheus response for instant query: code={}", response);
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new JSONObject();
+    }
     return jsonObject.getJSONObject("data");
   }
 
@@ -167,6 +173,9 @@ public List<String> getLabels(Map<String, String> queryParams) throws IOExceptio
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new ArrayList<>();
+    }
     return toListOfLabels(jsonObject.getJSONArray("data"));
   }
 
@@ -182,6 +191,9 @@ public List<String> getLabel(String labelName, Map<String, String> queryParams)
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new ArrayList<>();
+    }
     return toListOfLabels(jsonObject.getJSONArray("data"));
   }
 
@@ -196,6 +208,9 @@ public Map<String, List<MetricMetadata>> getAllMetrics(Map<String, String> query
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new HashMap<>();
+    }
     TypeReference<HashMap<String, List<MetricMetadata>>> typeRef = new TypeReference<>() {};
     return new ObjectMapper().readValue(jsonObject.getJSONObject("data").toString(), typeRef);
   }
@@ -215,6 +230,9 @@ public List<Map<String, String>> getSeries(Map<String, String> queryParams) thro
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new ArrayList<>();
+    }
     JSONArray dataArray = jsonObject.getJSONArray("data");
     return toListOfSeries(dataArray);
   }
@@ -232,6 +250,9 @@ public JSONArray queryExemplars(String query, Long start, Long end) throws IOExc
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new JSONArray();
+    }
     return jsonObject.getJSONArray("data");
   }
 
@@ -243,6 +264,9 @@ public JSONObject getAlerts() throws IOException {
     Request request = new Request.Builder().url(queryUrl).build();
     Response response = AccessController.doPrivilegedChecked(() -> this.prometheusHttpClient.newCall(request).execute());
     JSONObject jsonObject = readResponse(response);
+    if (!jsonObject.has("data")) {
+      return new JSONObject();
+    }
     return jsonObject.getJSONObject("data");
   }
 
diff --git a/direct-query-core/src/test/java/org/opensearch/sql/prometheus/client/PrometheusClientImplTest.java b/direct-query-core/src/test/java/org/opensearch/sql/prometheus/client/PrometheusClientImplTest.java
index c71f2852ac9..5c65ade2b18 100644
--- a/direct-query-core/src/test/java/org/opensearch/sql/prometheus/client/PrometheusClientImplTest.java
+++ b/direct-query-core/src/test/java/org/opensearch/sql/prometheus/client/PrometheusClientImplTest.java
@@ -1119,4 +1119,109 @@ public void testGetAlertmanagerStatusHttpErrorWithNullBody() throws IOException
             PrometheusClientException.class, () -> nullBodyClient.getAlertmanagerStatus());
     assertTrue(exception.getMessage().contains("No response body"));
   }
+
+  // Prometheus-compatible backends (e.g. Cortex) may return {"status":"success"} with no
+  // "data" key when there is nothing to report. Each of the following tests verifies the
+  // corresponding client method returns an empty result instead of throwing JSONException.
+
+  @Test
+  public void testGetAllMetricsReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    var result = client.getAllMetrics();
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testGetAllMetricsWithParamsReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    HashMap<String, String> params = new HashMap<>();
+    params.put("limit", "10");
+    var result = client.getAllMetrics(params);
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testQueryRangeReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    JSONObject result = client.queryRange("up", 1435781430L, 1435781460L, "15s");
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testQueryReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    JSONObject result = client.query("up", 1435781460L, 100, 30);
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testGetLabelsReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    List<String> result = client.getLabels(new HashMap<>());
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testGetLabelReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    List<String> result = client.getLabel("job", new HashMap<>());
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testGetSeriesReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    var result = client.getSeries(new HashMap<>());
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
+
+  @Test
+  public void testQueryExemplarsReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    JSONArray result = client.queryExemplars("http_request_duration_seconds_bucket", 1L, 2L);
+
+    assertNotNull(result);
+    assertEquals(0, result.length());
+  }
+
+  @Test
+  public void testGetAlertsReturnsEmptyWhenDataFieldMissing() throws IOException {
+    String emptyResponse = "{\"status\":\"success\"}";
+    mockWebServer.enqueue(new MockResponse().setBody(emptyResponse));
+
+    JSONObject result = client.getAlerts();
+
+    assertNotNull(result);
+    assertTrue(result.isEmpty());
+  }
 }