The 22-year-old has this season starred for Scotland in the HSBC Sevens World Series, scoring five tries in his first two tournaments in Wellington and Las Vegas.
McGuigan, who grew up in Cape Town but has a Glaswegian mother, has set his sights on proving an instant success at Scotstoun, telling the club's 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."
He added: "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 7s 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."
McGuigan emerged from the Western Province academy before winning a contract at the Border Bulldogs two years ago.
Warriors head coach Sean Lineen said: "Byron is a player with real potential. We've kept a keen eye on him during his involvement with the Scotland 7s 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."
Warriors managing director Nathan Bombrys said: "We're really pleased to have Byron on board. He's an exciting player and someone who will help us to build upon the positive momentum of the current season."
McGuigan's signing takes to five the new additions to the Warriors squad for season 2012/13. All Black back rower Angus MacDonald, Tonga World Cup number eight Villiami Ma'afu, reigning Newcastle Falcons Player of the Season lock Tim Swinson and returning fans' favourite Sean Lamont have all been secured.