diff --git a/moto/iotdata/responses.py b/moto/iotdata/responses.py
index fe085c6cf..ca35653d9 100644
--- a/moto/iotdata/responses.py
+++ b/moto/iotdata/responses.py
@@ -1,6 +1,7 @@
 from moto.core.responses import BaseResponse
 from .models import iotdata_backends, IoTDataPlaneBackend
 import json
+from typing import Any
 from urllib.parse import unquote
 
 
@@ -8,6 +9,11 @@ class IoTDataPlaneResponse(BaseResponse):
     def __init__(self) -> None:
         super().__init__(service_name="iot-data")
 
+    def setup_class(
+        self, request: Any, full_url: str, headers: Any, use_raw_body: bool = False
+    ) -> None:
+        super().setup_class(request, full_url, headers, use_raw_body=True)
+
     def _get_action(self) -> str:
         if self.path and self.path.startswith("/topics/"):
             # Special usecase - there is no way identify this action, besides the URL
diff --git a/tests/test_iotdata/test_iotdata.py b/tests/test_iotdata/test_iotdata.py
index 59df5c06d..d935e47c8 100644
--- a/tests/test_iotdata/test_iotdata.py
+++ b/tests/test_iotdata/test_iotdata.py
@@ -112,14 +112,14 @@ def test_publish():
     client = boto3.client("iot-data", region_name=region_name)
     client.publish(topic="test/topic1", qos=1, payload=b"pl1")
     client.publish(topic="test/topic2", qos=1, payload=b"pl2")
-    client.publish(topic="test/topic3", qos=1, payload=b"pl3")
+    client.publish(topic="test/topic3", qos=1, payload=b"\xbf")
 
     if not settings.TEST_SERVER_MODE:
         mock_backend = moto.iotdata.models.iotdata_backends[ACCOUNT_ID][region_name]
         mock_backend.published_payloads.should.have.length_of(3)
-        mock_backend.published_payloads.should.contain(("test/topic1", "pl1"))
-        mock_backend.published_payloads.should.contain(("test/topic2", "pl2"))
-        mock_backend.published_payloads.should.contain(("test/topic3", "pl3"))
+        mock_backend.published_payloads.should.contain(("test/topic1", b"pl1"))
+        mock_backend.published_payloads.should.contain(("test/topic2", b"pl2"))
+        mock_backend.published_payloads.should.contain(("test/topic3", b"\xbf"))
 
 
 @mock_iot