Cap badge Canadian Scottish Regiment , 3th Canadian Infantry Division

Details from the 1st Battalion were called out on service on 26 August 1939 and then placed on active service on 1 September 1939, under the designation 1st Battalion, The Canadian Scottish Regiment, CASF (Details), for local protection duties. Details from the 2nd Battalion were placed on active service on 1 September 1939, under the designation 2nd Battalion, The Canadian Scottish Regiment (Machine Gun), CASF (Details), for local protection duties. Details from the 62nd Field Battery, RCA were placed on active service on 1 September 1939, under the designation 62nd Field Battery (H), RCA, CASF (Details), for local protection duties. These details were disbanded on 31 December 1940.

The regiment mobilized the 1st Battalion, The Canadian Scottish Regiment, CASF, on 24 May 1940. It embarked for Britain on 25 August 1941. On D-Day, 6 June 1944, it landed in Normandy, France, as part of the 7th Infantry Brigade, 3rd Canadian Infantry Division, and it continued to fight in North-West Europe until the end of the war. The overseas battalion was disbanded on 15 January 1946.

The regiment subsequently mobilized the 2nd (Reserve) Battalion as the 2nd Battalion, The Canadian Scottish Regiment, CASF, on 1 January 1941. It served in Canada in a home defence role as part of the 13th Infantry Brigade, 6th Canadian Infantry Division. The battalion was disbanded on 15 October 1943.

On 1 June 1945, a third Active Force component of the regiment, designated the 4th Battalion, The Canadian Scottish Regiment, CIC, Canadian Army Occupation Force, was mobilized for service in post-war Germany. The battalion was disbanded on 29 April 1946.

The 62nd Field Battery, in conjunction with the 44th Field Battery, RCA, mobilized the 44th/62nd Field Battery, RCA, CASF, for active service on 24 May 1940. This unit was reorganized as two separate batteries on 1 January 1941, designated the 44th Field Battery, RCA, CASF, and the 62nd Field Battery, RCA, CASF. It was redesignated the 62nd Light Anti-Aircraft Battery, RCA, CASF, the same day. The battery provided light anti-aircraft artillery support as part of the 11th Light Anti-Aircraft Regiment, RCA, CASF, 1st Canadian Anti-Aircraft Brigade in Great Britain. The overseas battery was disbanded on 1 March 1944.