The Canadian international will remain with the Warriors until the end of October.
After his first training session with the squad, Chauncey told glasgowwarriors.org: "I'm really excited to be here. It's a great opportunity for me to get what is my first professional contract with a club like Glasgow."
Back in Canada, Chauncey played with Atlantic Rock but recently spent time with RGC 1404, a rugby development initiative between Rugby Canada and the Welsh Rugby Union, where he helped develop rugby, and his own skills, in North Wales as part of a nine-man Canadian contingent.
The 6ft 2ins, 15st O'Toole, now believed to be the first professional rugby player to be produced by Canada's New Brunswick Rugby Union, played rugby at school but returned to it after a spell in professional ice-hockey in Canada, playing for the Miramichi Timberwolves in the Maritime Junior A hockey league.
The 24-year-old has won six caps for Canada since his Test debut against Ireland in 2009. He took part in the Churchill Cup over the summer where he was named Man of the Match in Canada's 48-6 victory over Uruguay and scored a try in the final against England Saxons. He has also represented Canada 7s on the IRB Sevens World Series circuit.
Glasgow head coach Sean Lineen said of the new recruit: "This really came about through DTH [van der Merwe] who was playing for Canada through the summer.
"He looked at the fact that we didn't have our full contingent of back-row players and he said that this lad had been outstanding in the Churchill Cup and needed game-time.
"So we got him across and I liked what I saw. I'm expecting big things from him over the next couple of months."
Chauncey joins two other Canadian internationalists at the Warriors - Kevin Tkachuk and Van der Merwe - bolstering Glasgow's international count to 17 players.
On having some familiar faces to help integrate him into his new club and city, Chauncey said: "It's really nice having those guys here. I probably wouldn't be here without those guys. They've been a big help."
On his objectives with Glasgow, he concluded: "My ambition is to make the most of this opportunity and to try and earn a spot in the line-up as often as possible.
"Canada have their November tour coming up, which is in Europe this year, so I hope to be a part of that."