diff --git a/homeassistant/components/co2signal/diagnostics.py b/homeassistant/components/co2signal/diagnostics.py
new file mode 100644
index 00000000000..24f47f96da0
--- /dev/null
+++ b/homeassistant/components/co2signal/diagnostics.py
@@ -0,0 +1,23 @@
+"""Diagnostics support for CO2Signal."""
+from __future__ import annotations
+
+from homeassistant.components.diagnostics import async_redact_data
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import CONF_API_KEY
+from homeassistant.core import HomeAssistant
+
+from . import DOMAIN, CO2SignalCoordinator
+
+TO_REDACT = {CONF_API_KEY}
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, config_entry: ConfigEntry
+) -> dict:
+    """Return diagnostics for a config entry."""
+    coordinator: CO2SignalCoordinator = hass.data[DOMAIN][config_entry.entry_id]
+
+    return {
+        "config_entry": async_redact_data(config_entry.as_dict(), TO_REDACT),
+        "data": coordinator.data,
+    }
diff --git a/tests/components/co2signal/test_diagnostics.py b/tests/components/co2signal/test_diagnostics.py
new file mode 100644
index 00000000000..f84cb5e84df
--- /dev/null
+++ b/tests/components/co2signal/test_diagnostics.py
@@ -0,0 +1,32 @@
+"""Test the CO2Signal diagnostics."""
+from unittest.mock import patch
+
+from homeassistant.components.co2signal import DOMAIN
+from homeassistant.components.diagnostics import REDACTED
+from homeassistant.const import CONF_API_KEY
+from homeassistant.setup import async_setup_component
+
+from . import VALID_PAYLOAD
+
+from tests.common import MockConfigEntry
+from tests.components.diagnostics import get_diagnostics_for_config_entry
+
+
+async def test_entry_diagnostics(hass, hass_client):
+    """Test config entry diagnostics."""
+    config_entry = MockConfigEntry(
+        domain=DOMAIN, data={CONF_API_KEY: "", "location": ""}
+    )
+    config_entry.add_to_hass(hass)
+    with patch("CO2Signal.get_latest", return_value=VALID_PAYLOAD):
+        assert await async_setup_component(hass, DOMAIN, {})
+
+    result = await get_diagnostics_for_config_entry(hass, hass_client, config_entry)
+
+    config_entry_dict = config_entry.as_dict()
+    config_entry_dict["data"][CONF_API_KEY] = REDACTED
+
+    assert result == {
+        "config_entry": config_entry_dict,
+        "data": VALID_PAYLOAD,
+    }