James Stewart was born in Belfast in 1931. He attended Grosvenor Grammar School. He worked in the catering business.

Stewart was elected to the Belfast Corporation in 1967 and, following the reorganisation of local government, served on Belfast City Council. Stewart sat on the Council's Finance Committee, General Purposes Committee and Police Committee. He was Chairman of the Improvement Committee and was involved in road and transportation strategy for Belfast.

Stewart was appointed High Sheriff of Belfast in 1975. He served as Chairman of the Fire Authority for Northern Ireland and was a member of the National Joint Council of Fire Authorities for the United Kingdom

He had a particular interest in youth work and was active in the Boys' Brigade.