Leith, Edinburgh born inside right Freddie Forbes began his football career with Leith Benburb but came into the professional ranks fairly belatedly after serving with the 57th Field Division of The Royal Engineers during the First World War, winning the Military Medal for his bravery. He joined Scottish League club Heart of Midlothian from Leith Benburb in April 1920, making his Scottish League debut at Clyde that August already aged 26. While at Hearts he was close friends and trained with the famous Scottish Olympian athlete Eric Liddell. In his first full season with the club, he scored 24 League goals in 29 appearances as they finished third in the First Division. He scored 36 goals in 66 appearances for The Jambos over his two seasons at Tynecastle before being sold to First Division Everton in the 1922 close season, making his Football League debut against Newcastle United that September.
Despite four goals he made only 10 appearances for The Toffees in his debut season, and was a fringe player for two further seasons appearing only 4 more times for Everton before joining Third Division (South) club Plymouth Argyle in March 1925 in a deal that also saw teammate and former England international Jack Cock move to Home Park, then helping The Pilgrims to finish League runners up by the season end.
A regular marksman for The Pilgrims, Forbes was a near ever present missing just one match over the next two seasons as they again finished runners up in 1925-26 and 1926-27, and he remained a regular as they finished third and fourth in his final two seasons at Home Park. His special day came in the first match of the 1927-28 season, when he scored 4 out of 5 goals in a 5-0 win over Merthyr Town but in October the same season he also scored a hat-trick in 4-2 win over Norwich City. After 53 goals in 166 appearances for Plymouth Argyle, he joined Bristol Rovers in November 1929, where his two seasons at Eastville saw him score 14 goals in 70 appearances for The Pirates.
Forbes returned to Scotland joining Leith Athletic in July 1931 and had a brief spell with his hometown club before joining North Eastern League club Workington later the same year. Forbes saw a return to Football League action when he joined Third Division (South) club Northampton Town in July 1932, already aged 38. He had a single season at The County Ground, scoring 3 goals in 37 appearances for The Cobblers, before he finished his career back in Scotland with Airdrieonians.