Blythswood, Glasgow born inside forward Duncan Ronaldson began his football career with junior clubs Vale of Clyde in 1898 and Rutherglen Glencairn in 1899 before joining Southern League Queen’s Park Rangers in December 1900 on the recommendation of George Newlands, with whom he also played later at Norwich City.
After half a season at Loftus Road he was signed by First Division Grimsby Town in May 1901 and made his Football League debut against Derby County that September, missing only one game during his debut season and top scoring for The Mariners with 10 goals as they narrowly maintained their top flight status, however despite a further 10 goals from Ronaldson in 1902-03, when he joint top scored with Bill Appleyard, Grimsby were relegated at the end of the season and he joined FA Cup holders Bury in May 1903 after 20 goals in 68 appearances.
He stayed a single season at Gigg Lane, scoring 4 goals in 15 appearances, before returning to Queen’s Park Rangers in May 1904. After another season at Loftus Road, he then moved to various Southern League clubs, playing for Norwich City in their first professional side from May 1905 to the summer of 1907, when he joined Brighton & Hove Albion for a season where he scored 6 goals in 19 appearances. He then moved to Southend United in the summer of 1908 for a season before re-joining Norwich City in May 1909. He finally returned to Scotland in 1910 to join Dunfermline Athletic, where he finished his career.