diff --git a/homeassistant/components/mqtt/debug_info.py b/homeassistant/components/mqtt/debug_info.py
index e462d76fa31..3e32d301b70 100644
--- a/homeassistant/components/mqtt/debug_info.py
+++ b/homeassistant/components/mqtt/debug_info.py
@@ -139,7 +139,7 @@ async def info_for_device(hass, device_id):
                 "topic": topic,
                 "messages": [
                     {
-                        "payload": msg.payload,
+                        "payload": str(msg.payload),
                         "qos": msg.qos,
                         "retain": msg.retain,
                         "time": msg.timestamp,
diff --git a/tests/components/mqtt/test_common.py b/tests/components/mqtt/test_common.py
index 593d08f4c87..78c37b1105a 100644
--- a/tests/components/mqtt/test_common.py
+++ b/tests/components/mqtt/test_common.py
@@ -1222,7 +1222,7 @@ async def help_test_entity_debug_info_message(
         "topic": topic,
         "messages": [
             {
-                "payload": payload,
+                "payload": str(payload),
                 "qos": 0,
                 "retain": False,
                 "time": start_dt,
diff --git a/tests/components/mqtt/test_init.py b/tests/components/mqtt/test_init.py
index a71c332b70b..9101b895218 100644
--- a/tests/components/mqtt/test_init.py
+++ b/tests/components/mqtt/test_init.py
@@ -3,7 +3,7 @@ import asyncio
 from datetime import datetime, timedelta
 import json
 import ssl
-from unittest.mock import AsyncMock, MagicMock, call, mock_open, patch
+from unittest.mock import ANY, AsyncMock, MagicMock, call, mock_open, patch
 
 import pytest
 import voluptuous as vol
@@ -1540,6 +1540,68 @@ async def test_mqtt_ws_get_device_debug_info(
     assert response["result"] == expected_result
 
 
+async def test_mqtt_ws_get_device_debug_info_binary(
+    hass, device_reg, hass_ws_client, mqtt_mock
+):
+    """Test MQTT websocket device debug info."""
+    config = {
+        "device": {"identifiers": ["0AFFD2"]},
+        "platform": "mqtt",
+        "topic": "foobar/image",
+        "unique_id": "unique",
+    }
+    data = json.dumps(config)
+
+    async_fire_mqtt_message(hass, "homeassistant/camera/bla/config", data)
+    await hass.async_block_till_done()
+
+    # Verify device entry is created
+    device_entry = device_reg.async_get_device({("mqtt", "0AFFD2")})
+    assert device_entry is not None
+
+    small_png = (
+        b"\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x04\x00\x00\x00\x04\x08\x06"
+        b"\x00\x00\x00\xa9\xf1\x9e~\x00\x00\x00\x13IDATx\xdac\xfc\xcf\xc0P\xcf\x80\x04"
+        b"\x18I\x17\x00\x00\xf2\xae\x05\xfdR\x01\xc2\xde\x00\x00\x00\x00IEND\xaeB`\x82"
+    )
+    async_fire_mqtt_message(hass, "foobar/image", small_png)
+    await hass.async_block_till_done()
+
+    client = await hass_ws_client(hass)
+    await client.send_json(
+        {"id": 5, "type": "mqtt/device/debug_info", "device_id": device_entry.id}
+    )
+    response = await client.receive_json()
+    assert response["success"]
+    expected_result = {
+        "entities": [
+            {
+                "entity_id": "camera.mqtt_camera",
+                "subscriptions": [
+                    {
+                        "topic": "foobar/image",
+                        "messages": [
+                            {
+                                "payload": str(small_png),
+                                "qos": 0,
+                                "retain": False,
+                                "time": ANY,
+                                "topic": "foobar/image",
+                            }
+                        ],
+                    }
+                ],
+                "discovery_data": {
+                    "payload": config,
+                    "topic": "homeassistant/camera/bla/config",
+                },
+            }
+        ],
+        "triggers": [],
+    }
+    assert response["result"] == expected_result
+
+
 async def test_debug_info_multiple_devices(hass, mqtt_mock):
     """Test we get correct debug_info when multiple devices are present."""
     devices = [