He was previously part of Glasgow's EDP group.
Fergus is a product of Currie, has represented Scotland under-20s and although he has yet to make his competitive debut for the club, he featured in the pre-season friendly with Harlequins and has played for the Warriors 'A' side this season.
He played club rugby with Ayr last season.
Fergus said: "I'm delighted to take the next step up and sign my first professional contract with the Warriors, after spending the last three seasons in the academy set-up.
"This is a big opportunity for me and my aim is to work hard and compete with the other hookers at the club."