diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1a27324ce..d1b792cc2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@
   * `SAFE_AREA` mode: Omits status bar, navigation bar and cutouts when displaying webviews.
 * Added a new init config option `disableGradualRequestCleaner()` to change request queue overflow behavior. When enabled, all overflowing requests (plus one slot) are removed at once instead of being cleaned gradually in limited batches.
 
+* Added a new method `requestQueue().addCustomNetworkRequestHeaders(Map<String,String>)` for providing or overriding custom headers after init 
+
 * Immediate requests now will be run by parallel executor instead of serial by default.
 
 ## 25.4.4
diff --git a/sdk/src/androidTest/java/ly/count/android/sdk/CustomHeaderRuntimeTests.java b/sdk/src/androidTest/java/ly/count/android/sdk/CustomHeaderRuntimeTests.java
new file mode 100644
index 000000000..7ff64cc6e
--- /dev/null
+++ b/sdk/src/androidTest/java/ly/count/android/sdk/CustomHeaderRuntimeTests.java
@@ -0,0 +1,63 @@
+package ly.count.android.sdk;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import java.net.URLConnection;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for runtime custom header manipulation via Countly.addCustomNetworkRequestHeaders(Map<String,String>)
+ */
+@RunWith(AndroidJUnit4.class)
+public class CustomHeaderRuntimeTests {
+
+    Countly mCountly;
+
+    @Before
+    public void setUp() {
+        final CountlyStore countlyStore = new CountlyStore(TestUtils.getContext(), mock(ModuleLog.class));
+        countlyStore.clear();
+
+        mCountly = new Countly();
+        mCountly.init(new CountlyConfig(TestUtils.getContext(), "appkey", "http://test.count.ly").setDeviceId("1234").setLoggingEnabled(true));
+    }
+
+    @Test
+    public void testRuntimeAddAndOverrideHeaders() throws Exception {
+        // Add initial headers at runtime
+        Map<String, String> initial = new HashMap<>();
+        initial.put("X-First", "One");
+        initial.put("X-Second", "Two");
+        mCountly.requestQueue().addCustomNetworkRequestHeaders(initial);
+
+        // Override one and add a new one
+        Map<String, String> second = new HashMap<>();
+        second.put("X-Second", "TwoOverride");
+        second.put("X-Third", "Three");
+        mCountly.requestQueue().addCustomNetworkRequestHeaders(second);
+
+        ConnectionProcessor cp = new ConnectionProcessor(
+            "http://test.count.ly",
+            mCountly.countlyStore,
+            mCountly.config_.deviceIdProvider,
+            mCountly.config_.configProvider,
+            mCountly.connectionQueue_.requestInfoProvider,
+            null,
+            mCountly.requestHeaderCustomValues,
+            mCountly.L,
+            mCountly.config_.healthTracker,
+            mock(Runnable.class)
+        );
+
+        URLConnection urlConnection = cp.urlConnectionForServerRequest("a=b", null);
+
+        Assert.assertEquals("One", urlConnection.getRequestProperty("X-First"));
+        Assert.assertEquals("TwoOverride", urlConnection.getRequestProperty("X-Second"));
+        Assert.assertEquals("Three", urlConnection.getRequestProperty("X-Third"));
+    }
+}
diff --git a/sdk/src/main/java/ly/count/android/sdk/Countly.java b/sdk/src/main/java/ly/count/android/sdk/Countly.java
index c89a32dc0..de8e42595 100644
--- a/sdk/src/main/java/ly/count/android/sdk/Countly.java
+++ b/sdk/src/main/java/ly/count/android/sdk/Countly.java
@@ -1157,6 +1157,49 @@ public void setLoggingEnabled(final boolean enableLogging) {
         L.d("Enabling logging");
     }
 
+    /**
+     * To add new header key/value pairs or override existing ones.
+     * A null or empty map is ignored. Null or empty keys, as well as null values, are ignored.
+     * Subsequent requests (including those created after overriding) will contain the updated header set.
+     *
+     * @param customHeaderValues map of header key/value pairs to add/override
+     * @return Returns the same Countly instance for convenient chaining
+     */
+    /* package */ synchronized void addCustomNetworkRequestHeaders(Map<String, String> customHeaderValues) {
+        if (!isInitialized()) {
+            L.e("[addCustomNetworkRequestHeaders] SDK must be initialised before calling this method");
+            return;
+        }
+
+        if (customHeaderValues == null || customHeaderValues.isEmpty()) {
+            L.d("[addCustomNetworkRequestHeaders] Provided map was null or empty, ignoring");
+            return;
+        }
+
+        if (requestHeaderCustomValues == null) {
+            requestHeaderCustomValues = new HashMap<>();
+        }
+
+        int added = 0;
+        int overridden = 0;
+        for (Map.Entry<String, String> entry : customHeaderValues.entrySet()) {
+            String k = entry.getKey();
+            String v = entry.getValue();
+            if (k == null || k.isEmpty() || v == null) {
+                continue; // skip invalid entries
+            }
+            if (requestHeaderCustomValues.containsKey(k)) {
+                overridden++;
+            } else {
+                added++;
+            }
+            requestHeaderCustomValues.put(k, v);
+        }
+
+        connectionQueue_.setRequestHeaderCustomValues(requestHeaderCustomValues);
+        L.i("[addCustomNetworkRequestHeaders] Added:" + added + " Overridden:" + overridden + " TotalNow:" + requestHeaderCustomValues.size());
+    }
+
     /**
      * Check if logging has been enabled internally in the SDK
      *
diff --git a/sdk/src/main/java/ly/count/android/sdk/ModuleRequestQueue.java b/sdk/src/main/java/ly/count/android/sdk/ModuleRequestQueue.java
index abd1bb4c9..d446bee4e 100644
--- a/sdk/src/main/java/ly/count/android/sdk/ModuleRequestQueue.java
+++ b/sdk/src/main/java/ly/count/android/sdk/ModuleRequestQueue.java
@@ -456,5 +456,21 @@ public void recordMetrics(@Nullable Map<String, String> metricsOverride) {
                 recordMetricsInternal(tempMetricsOverride);
             }
         }
+
+        /**
+         * To add new header key/value pairs or override existing ones.
+         * A null or empty map is ignored. Null or empty keys, as well as null values,
+         * are ignored.
+         * Subsequent requests (including those created after overriding) will contain
+         * the updated header set.
+         *
+         * @param customHeaderValues header key/value pairs to add or override
+         */
+        public void addCustomNetworkRequestHeaders(@Nullable Map<String, String> customHeaderValues) {
+            synchronized (_cly) {
+                L.i("[RequestQueue] addCustomNetworkRequestHeaders, Calling addCustomNetworkRequestHeaders");
+                _cly.addCustomNetworkRequestHeaders(customHeaderValues);
+            }
+        }
     }
 }