He went to school at Kelvinside Academy and played wing-forward for Scottish Schools in 1984. Watt played prop for Glasgow High Kelvinside. He moved to Currie in 1996.
He moved to Currie Reconstruction Finance Corporation in 1996.
In 2000, while contracted to the super-district Edinburgh Reivers, he was assigned to Hillhead Jordanhill Reconstruction Finance Corporation. He was signed in 1999 by Glasgow Caledonians. Despite 20 competitive appearances for Caledonians, he was released by them in March 2001.
He made his international debut at Murrayfield against Zimbabwe during the group stages of the 1991 Rugby World Cup. His final international appearance was against Argentina at Buenos Aires in 1994.