diff --git a/CHANGELOG.md b/CHANGELOG.md
index def7f7c..fa98e76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 1.1.0 (2026-08-12)
+
+- `CreateLogEntries` now accepts a payload that is already encoded as JSON `bytes` and sends those bytes
+  as the request body unchanged. Callers that serialize an entry for their own reasons, such as validating
+  it before upload, can pass the result through instead of encoding the same payload twice.
+
 ## 1.0.0 (2026-07-31)
 
 - Use `msgspec` for all JSON encoding and decoding, with a `ujson` fallback for types `msgspec` cannot serialize natively (such as `numpy` scalars and arrays).
diff --git a/python/mujintestwebstackclient/test_webstackclient.py b/python/mujintestwebstackclient/test_webstackclient.py
index 48fae7b..95f876a 100644
--- a/python/mujintestwebstackclient/test_webstackclient.py
+++ b/python/mujintestwebstackclient/test_webstackclient.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import msgspec
 import pytest
 import requests_mock
 import random
@@ -7,6 +8,8 @@
 import copy
 import graphql
 
+from unittest import mock
+
 from mujinwebstackclient.webstackclient import WebstackClient
 from mujinwebstackclient.webstackclientutils import QueryIterator, GetMaximumQueryLimit
 from mujinwebstackclient.webstackgraphclientutils import GraphQueryIterator
@@ -489,3 +492,32 @@ def test_LazyQueryStandardListOperations():
         del scenes[start:end]
         del expectedScenes[start:end]
         assert scenes == expectedScenes
+
+
+def test_CreateLogEntriesAcceptsPreEncodedPayloads():
+    """A payload handed over as JSON bytes must reach the request body unchanged.
+
+    Callers that already serialized an entry, such as to validate it before uploading, rely on this to avoid
+    encoding a second copy of every payload they send.
+    """
+    webstackclient = WebstackClient.__new__(WebstackClient)
+    webstackclient._webclient = mock.Mock()
+    webstackclient._webclient.EncodeJSON.side_effect = msgspec.json.Encoder().encode
+
+    logEntry = {
+        'occurredAt': '2026-08-12T00:00:00Z',
+        'version': 1,
+        'soukoExecutionTask': {'taskId': 'aeon_cycleCount:C6E3KZP5K1LQMQL5', 'taskType': 'aeon_cycleCount'},
+    }
+
+    webstackclient.CreateLogEntries(logEntries=[('SoukoExecutionTask', logEntry, {})])
+    filesFromDict = webstackclient._webclient.APICall.call_args.kwargs['files']
+
+    webstackclient._webclient.reset_mock()
+    webstackclient.CreateLogEntries(logEntries=[('SoukoExecutionTask', msgspec.json.encode(logEntry), {})])
+    filesFromBytes = webstackclient._webclient.APICall.call_args.kwargs['files']
+
+    # Both forms put the same bytes on the wire, so a caller can switch to the encoded form freely.
+    assert filesFromBytes == filesFromDict
+    # The encoded payload went out as given rather than being run through the encoder again.
+    webstackclient._webclient.EncodeJSON.assert_not_called()
diff --git a/python/mujinwebstackclient/version.py b/python/mujinwebstackclient/version.py
index ce4357f..0308f96 100644
--- a/python/mujinwebstackclient/version.py
+++ b/python/mujinwebstackclient/version.py
@@ -1,3 +1,3 @@
-__version__ = '1.0.0'
+__version__ = '1.1.0'
 
 # Do not forget to update CHANGELOG.md
diff --git a/python/mujinwebstackclient/webstackclient.py b/python/mujinwebstackclient/webstackclient.py
index 88d197a..78ce824 100644
--- a/python/mujinwebstackclient/webstackclient.py
+++ b/python/mujinwebstackclient/webstackclient.py
@@ -11,7 +11,7 @@
 from email.utils import parsedate
 
 import six
-from typing import List, Tuple, Any, Dict  # noqa: F401
+from typing import List, Tuple, Any, Dict, Union  # noqa: F401
 
 # Mujin imports
 from . import WebstackClientError
@@ -675,10 +675,17 @@ def DeleteJobs(self, timeout=5):
     #
 
     def CreateLogEntries(self, logEntries, timeout=5):
-        # type: (List[Tuple[str, Any, Dict[str, bytes]]], float) -> Any
+        # type: (List[Tuple[str, Union[bytes, Any], Dict[str, bytes]]], float) -> Any
+        """Uploads log entries given as (log type, payload, attachments) tuples.
+
+        A payload may be passed as the JSON bytes of an already-encoded entry.
+        Callers may have already serialized it to e.g. ensure that it serializes correctly,
+        and if they have, it makes sense to re-use that already serialized data.
+        """
         files = []
         for logType, logEntry, attachments in logEntries:
-            files.append(('logEntry/%s' % logType, ('', self._webclient.EncodeJSON(logEntry), 'application/json')))
+            body = logEntry if isinstance(logEntry, bytes) else self._webclient.EncodeJSON(logEntry)
+            files.append(('logEntry/%s' % logType, ('', body, 'application/json')))
             if attachments is not None:
                 for attachmentName, attachmentData in six.iteritems(attachments):
                     files.append(('attachment', (attachmentName, attachmentData)))