Robertson played amateur rugby for Stirling County. He was part of a formidable front three in the forward pack;[2] his Stirling County teammate Stewart Hamilton in the book Giants of Scottish Rugby remembers: "We had a great side then particularly the pack.The front row was Brian Robertson, Kevin McKenzie and George Graham. Brian unfortunately had a bad neck injury but the other two went on to play for Scotland." Coached by Richie Dixon, the County team won promotion from Division 2 and then won Division 1 in season 1994-95.[3]
He also represented the provincial side Glasgow District in the amateur era.[4] He was part of Glasgow's touring squad that played the Netherlands and Belgium[5]
He was in Glasgow District's famous 1989-90 side which won the Scottish Inter-District Championship that season; winning outright the title for only the third time in Glasgow's history.[6] That season Glasgow went unbeaten against allcomers, including the touring Fiji national rugby union team[7] although Robertson missed Glasgow's Irish tour that year.[8]
In 1992 he received a shoulder injury and was dropped by the Glasgow side.[9] However this break wasn't for long and he came back for Glasgow's next match.[10]
He played for the amateur district until 1996[11] when they turned professional.
Robertson played in all 8 competitive matches for Glasgow Warriors in their first season; 3 matches in the 1996-97 Scottish Inter-District Championship and 5 matches in the European Conference, now European Challenge Cup. He started in the Warriors first professional match; and is Glasgow Warrior No. 3.
He was capped by Scotland 'B' and Scotland 'A' but never received a full senior cap.[12]
His first cap for the 'B' side was on 22 December 1990 against Ireland 'B'.[13]
The veteran tighthead became a coach at Stirling County. However he quit in 2004 stating that he wanted a break from rugby.[14]