The 22-year-old joins Glasgow after impressing in his first two Scotland Sevens tournaments in Wellington and Las Vegas - scoring five tries in the process.
McGuigan has put pen-to-paper on a two-year contract that will keep him at the club until at least the end of May 2014.
McGuigan, who emerged from the Western Province academy before winning a contract at the Border Bulldogs two years ago, told the Glasgow Warriors official website: "I'm proud and honoured to be joining a club like Glasgow Warriors who are on the way up and have ambitious plans for the future.
"The calibre of player in the squad is strong, there are lots of quality individuals signing and re-signing and the move to the great facilities at Scotstoun Stadium is going to help the club put down roots.
"I can't wait to sample the passion the rugby public in west of Scotland have for the game when the Glasgow Sevens takes place in three weeks' time, and I'm really looking forward to running out there in the Warriors black and blue when next season rolls around."
Warriors head coach Sean Lineen added: "Byron is a player with real potential. We've kept a keen eye on him during his involvement with the Scotland Sevens team, and we're convinced he has the right attributes to be an asset for Glasgow Warriors.
"He's strong, he's creative and he's got a great step and work ethic. He's primarily an outside centre, but he's capable of contributing strongly in any of the back three positions as well.
"We've been impressed with how keen he is to come here and prove himself in the RaboDirect PRO12 and Heineken Cup."
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