The 23rd Reserve Battalion, CEF was an infantry unit in the Canadian Expeditionary Force during the First World War.

The initial core of the battalion comprised trained recruits from The Canadian Grenadier Guards and the 58th Regiment Westmount Rifles.

[2] For the duration of the war, the 23rd Reserve Battalion, based in England, trained and provided reinforcements for Canadian infantry units fighting in France.

The unit routinely received reinforcements from Canada, both directly and through the absorption of other infantry battalions.

[2] The battalion was disbanded by general order on September 15, 1920, and is currently perpetuated by The Royal Montreal Regiment.