The Ceylon Defence Force (CDF) was established in 1910 by the Ceylonese legislation Ceylon Defence Force Ordinance, which reformed the Ceylon Volunteer Force (CVF) that existed previously as the military reserve in the British Crown colony of Ceylon. At the time of forming it was only a reserve force but soon developed into a regular force responsible for the defence of Ceylon. The CDF was under the command of the General Officer Commanding, Ceylon of the British Army in Ceylon if mobilised. However mobilisation could be carried out only under orders from the Governor.

Ceylon was an independent country in the Commonwealth of Nations from 1948 to 1972, that shared a monarch with other dominions of the Commonwealth. In 1948, the British Colony of Ceylon was granted independence as Ceylon. In 1972, the country became a republic within the Commonwealth, and its name was changed to Sri Lanka.