The Namibian-born back, who qualifies to play for Scotland, joined the club at the start of the 2012/13 season.
McGuigan made 20 appearances and scored four tries for the RaboDirect PRO12 side.
He won his first Scotland A cap in the draw with England Saxons in January.
Glasgow Warriors head coach Gregor Townsend said: "Byron has really developed since he joined us and it was great to see him play for Scotland A earlier this year and score on his debut.
"He has played in some key games for the club this season and we'd like to wish him all the best for the future."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland