diff --git a/source/_integrations/binary_sensor.markdown b/source/_integrations/binary_sensor.markdown
index 47fc263c988..fb769c6d3cf 100644
--- a/source/_integrations/binary_sensor.markdown
+++ b/source/_integrations/binary_sensor.markdown
@@ -46,6 +46,7 @@ The full list of supported binary sensor device classes is below
 - **None**: Generic on/off. This is the default and doesn't need to be set.
 - **battery**: `on` means low, `off` means normal
 - **battery_charging**: `on` means charging, `off` means not charging
+- **carbon_monoxide**: `on` means carbon monoxide detected, `off` no carbon monoxide (clear)
 - **cold**: `on` means cold, `off` means normal
 - **connectivity**: `on` means connected, `off` means disconnected
 - **door**: `on` means open, `off` means closed