The Welsh Office was a department in the Government of the United Kingdom with responsibilities for Wales. It was established in April 1965 to execute government policy in Wales, and was headed by the Secretary of State for Wales, a post which had been created in October 1964. It was disbanded on 1 July 1999 when most of its powers were transferred to the National Assembly for Wales, with some powers transferred to the Office of the Secretary of State for Wales, a department popularly known as the Wales Office.

The secretary of state for Wales, also referred to as the Welsh secretary, is a secretary of state in the Government of the United Kingdom, with responsibility for the Wales Office. The incumbent is a member of the Cabinet of the United Kingdom.