diff --git a/homeassistant/components/brother/diagnostics.py b/homeassistant/components/brother/diagnostics.py
new file mode 100644
index 00000000000..9ff515004cb
--- /dev/null
+++ b/homeassistant/components/brother/diagnostics.py
@@ -0,0 +1,24 @@
+"""Diagnostics support for Brother."""
+from __future__ import annotations
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+
+from . import BrotherDataUpdateCoordinator
+from .const import DATA_CONFIG_ENTRY, DOMAIN
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, config_entry: ConfigEntry
+) -> dict:
+    """Return diagnostics for a config entry."""
+    coordinator: BrotherDataUpdateCoordinator = hass.data[DOMAIN][DATA_CONFIG_ENTRY][
+        config_entry.entry_id
+    ]
+
+    diagnostics_data = {
+        "info": dict(config_entry.data),
+        "data": coordinator.data,
+    }
+
+    return diagnostics_data
diff --git a/tests/components/brother/fixtures/diagnostics_data.json b/tests/components/brother/fixtures/diagnostics_data.json
new file mode 100644
index 00000000000..1a8458e1caf
--- /dev/null
+++ b/tests/components/brother/fixtures/diagnostics_data.json
@@ -0,0 +1,45 @@
+{
+    "b/w_counter": 709,
+    "belt_unit_remaining_life": 97,
+    "belt_unit_remaining_pages": 48436,
+    "black_drum_counter": 1611,
+    "black_drum_remaining_life": 92,
+    "black_drum_remaining_pages": 16389,
+    "black_toner": 80,
+    "black_toner_remaining": 75,
+    "black_toner_status": 1,
+    "color_counter": 902,
+    "cyan_drum_counter": 1611,
+    "cyan_drum_remaining_life": 92,
+    "cyan_drum_remaining_pages": 16389,
+    "cyan_toner": 10,
+    "cyan_toner_remaining": 10,
+    "cyan_toner_status": 1,
+    "drum_counter": 986,
+    "drum_remaining_life": 92,
+    "drum_remaining_pages": 11014,
+    "drum_status": 1,
+    "duplex_unit_pages_counter": 538,
+    "firmware": "1.17",
+    "fuser_remaining_life": 97,
+    "laser_unit_remaining_pages": 48389,
+    "magenta_drum_counter": 1611,
+    "magenta_drum_remaining_life": 92,
+    "magenta_drum_remaining_pages": 16389,
+    "magenta_toner": 10,
+    "magenta_toner_remaining": 8,
+    "magenta_toner_status": 2,
+    "model": "HL-L2340DW",
+    "page_counter": 986,
+    "pf_kit_1_remaining_life": 98,
+    "pf_kit_1_remaining_pages": 48741,
+    "serial": "0123456789",
+    "status": "waiting",
+    "uptime": "2019-09-24T12:14:56+00:00",
+    "yellow_drum_counter": 1611,
+    "yellow_drum_remaining_life": 92,
+    "yellow_drum_remaining_pages": 16389,
+    "yellow_toner": 10,
+    "yellow_toner_remaining": 2,
+    "yellow_toner_status": 2
+}
diff --git a/tests/components/brother/test_diagnostics.py b/tests/components/brother/test_diagnostics.py
new file mode 100644
index 00000000000..7e25ffaa4f0
--- /dev/null
+++ b/tests/components/brother/test_diagnostics.py
@@ -0,0 +1,29 @@
+"""Test Brother diagnostics."""
+from datetime import datetime
+import json
+from unittest.mock import Mock, patch
+
+from homeassistant.util.dt import UTC
+
+from tests.common import load_fixture
+from tests.components.brother import init_integration
+from tests.components.diagnostics import get_diagnostics_for_config_entry
+
+
+async def test_entry_diagnostics(hass, hass_client):
+    """Test config entry diagnostics."""
+    entry = await init_integration(hass, skip_setup=True)
+
+    diagnostics_data = json.loads(load_fixture("diagnostics_data.json", "brother"))
+    test_time = datetime(2019, 11, 11, 9, 10, 32, tzinfo=UTC)
+    with patch("brother.datetime", utcnow=Mock(return_value=test_time)), patch(
+        "brother.Brother._get_data",
+        return_value=json.loads(load_fixture("printer_data.json", "brother")),
+    ):
+        await hass.config_entries.async_setup(entry.entry_id)
+        await hass.async_block_till_done()
+
+    result = await get_diagnostics_for_config_entry(hass, hass_client, entry)
+
+    assert result["info"] == {"host": "localhost", "type": "laser"}
+    assert result["data"] == diagnostics_data