Cap badge Lanark and Renfrew Scottish Regiment of Canada, 4th Canadian Division

The regiment did not initially mobilize for the Second World War during the general activation of units beginning in August 1939.

In July 1944, the 5th Canadian (Armoured) Division perceived it was deficient in infantry. The 12th Canadian Infantry Brigade was created out of units already in existence.[5] One unit of the new brigade was the Motor battalion of the division, a second was a re-equipped reconnaissance battalion from the 1st Canadian Infantry Division, and a third unit was created from anti-aircraft assets, no longer required due to Allied aerial superiority. This unit petitioned The Lanark and Renfrew Scottish for permission to use their name and regimental insignia, feeling it was more appropriate for an infantry battalion. Permission was granted, and The Lanark and Renfrew Scottish served in the 12th Brigade until March 1945. After all Canadian forces in Italy were repatriated to the command of 1st Canadian Army in North-west Europe, the brigade was dissolved, the units therein returned to their former roles, and the Lanark and Renfrew Scottish battalion was returned to its former duties and designation.