As a player McCandless normally played at left-back, most notably at Rangers where he won six Scottish Football League titles with the side.

He stayed with the Blues for six years, helping them to Irish Cup success in 1916 and 1919 before his performance in a 2–0 defeat to England while playing for Ireland prompted a number of British sides to show interest in signing him.

Eventually joining Rangers in 1920 for £2,500, a record fee for an Irish player at the time, he went on to add six Scottish Football League titles to his honours collection[4] while playing at Ibrox where he formed a formidable full back pairing with another Irishman, Bert Manderson.

He returned to Scotland in 1933 to take charge of Dundee before moving to Newport County in 1937, where he helped them to promotion to Division 2 in 1939 despite using just 13 players throughout the season.

A month later he was appointed Cardiff City manager in 1946 and took the side to the Division Three South title in his first year finishing nine points clear of second place Queens Park Rangers but, after only a few months of the following season, he left to join local rivals Swansea Town.