The Irish-born winger, who has a Scottish grandfather, previously represented the sevens side but has also played at age-grade level for Ireland.
"The opportunity to work under Warriors head coach Dave Rennie was a huge pull to come to Glasgow," McFarland told Warriors TV.
"One of my coaches back in Clontarf used to work with Dave and I've only ever heard the best of things, so I'm really looking forward to training under his guidance.
"The 7s are such a great group of boys, a good mix of experience and young fellas coming through and I'm excited to be involved with them as well as Glasgow."
Meanwhile, Jonny Gray is reported to be a target for Bristol.
A BBC report claims the English Championship side have made an offer to sign the 23-year-old lock, whose contract at Scotstoun expires at the end of this season.
It follows the news that fly-half Finn Russell is to leave the Warriors in the summer to join French Top 14 side Racing 92.
Gray's future is expected to be resolved before Christmas and it is understood to be a 50-50 decision on whether he stays at Glasgow or joins Bristol.