diff --git a/async_substrate_interface/async_substrate.py b/async_substrate_interface/async_substrate.py
index dcc5ceb..90ac49d 100644
--- a/async_substrate_interface/async_substrate.py
+++ b/async_substrate_interface/async_substrate.py
@@ -3467,7 +3467,9 @@ async def get_account_nonce(self, account_address: str) -> int:
             )
             return response["nonce"]
 
-    async def get_account_next_index(self, account_address: str) -> int:
+    async def get_account_next_index(
+        self, account_address: str, use_cache: bool = True
+    ) -> int:
         """
         This method maintains a cache of nonces for each account ss58address.
         Upon subsequent calls, it will return the cached nonce + 1 instead of fetching from the chain.
@@ -3475,22 +3477,30 @@ async def get_account_next_index(self, account_address: str) -> int:
 
         Args:
             account_address: SS58 formatted address
+            use_cache: If True, bypass local nonce cache and always request fresh value from RPC.
 
         Returns:
             Next index for the given account address
         """
+
+        async def _get_account_next_index():
+            """Inner RPC call to get `account_nextIndex`."""
+            nonce_obj_ = await self.rpc_request("account_nextIndex", [account_address])
+            if "error" in nonce_obj_:
+                raise SubstrateRequestException(nonce_obj_["error"]["message"])
+            return nonce_obj_["result"]
+
         if not await self.supports_rpc_method("account_nextIndex"):
             # Unlikely to happen, this is a common RPC method
             raise Exception("account_nextIndex not supported")
 
+        if not use_cache:
+            return await _get_account_next_index()
+
         async with self._lock:
             if self._nonces.get(account_address) is None:
-                nonce_obj = await self.rpc_request(
-                    "account_nextIndex", [account_address]
-                )
-                if "error" in nonce_obj:
-                    raise SubstrateRequestException(nonce_obj["error"]["message"])
-                self._nonces[account_address] = nonce_obj["result"]
+                nonce_obj = await _get_account_next_index()
+                self._nonces[account_address] = nonce_obj
             else:
                 self._nonces[account_address] += 1
         return self._nonces[account_address]
diff --git a/tests/unit_tests/asyncio_/test_substrate_interface.py b/tests/unit_tests/asyncio_/test_substrate_interface.py
index 632af81..afefe7a 100644
--- a/tests/unit_tests/asyncio_/test_substrate_interface.py
+++ b/tests/unit_tests/asyncio_/test_substrate_interface.py
@@ -11,6 +11,7 @@
     AsyncSubstrateInterface,
     get_async_substrate_interface,
 )
+from async_substrate_interface.errors import SubstrateRequestException
 from async_substrate_interface.types import ScaleObj
 from tests.helpers.settings import ARCHIVE_ENTRYPOINT, LATENT_LITE_ENTRYPOINT
 
@@ -287,3 +288,53 @@ async def test_cache_miss_fetches_and_stores(self, substrate):
         substrate.runtime_cache.add_item.assert_called_once_with(
             block_hash="0xABC", block=100
         )
+
+
+@pytest.mark.asyncio
+async def test_get_account_next_index_cached_mode_uses_internal_cache():
+    substrate = AsyncSubstrateInterface("ws://localhost", _mock=True)
+    substrate.supports_rpc_method = AsyncMock(return_value=True)
+    substrate.rpc_request = AsyncMock(return_value={"result": 5})
+
+    first = await substrate.get_account_next_index("5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA")
+    second = await substrate.get_account_next_index(
+        "5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA"
+    )
+
+    assert first == 5
+    assert second == 6
+    substrate.rpc_request.assert_awaited_once_with(
+        "account_nextIndex", ["5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA"]
+    )
+
+
+@pytest.mark.asyncio
+async def test_get_account_next_index_bypass_mode_does_not_create_or_mutate_cache():
+    substrate = AsyncSubstrateInterface("ws://localhost", _mock=True)
+    substrate.supports_rpc_method = AsyncMock(return_value=True)
+    substrate.rpc_request = AsyncMock(return_value={"result": 10})
+
+    address = "5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA"
+    assert address not in substrate._nonces
+
+    result = await substrate.get_account_next_index(
+        address,
+        use_cache=False,
+    )
+
+    assert result == 10
+    assert address not in substrate._nonces
+    substrate.rpc_request.assert_awaited_once_with("account_nextIndex", [address])
+
+
+@pytest.mark.asyncio
+async def test_get_account_next_index_bypass_mode_raises_on_rpc_error():
+    substrate = AsyncSubstrateInterface("ws://localhost", _mock=True)
+    substrate.supports_rpc_method = AsyncMock(return_value=True)
+    substrate.rpc_request = AsyncMock(return_value={"error": {"message": "rpc failure"}})
+
+    with pytest.raises(SubstrateRequestException, match="rpc failure"):
+        await substrate.get_account_next_index(
+            "5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA",
+            use_cache=False,
+        )