The Guinness PRO12 champions have signed stand-off Rory Clegg and Scottish club props George Hunter, Gary Strain and Steven Findlay on short-term contracts.
Fly-half Clegg joins from Newcastle Falcons after signing a short-term contract for the duration of the World Cup, subject to medical.
He made 55 appearances for Harlequins over four seasons at Twickenham Stoop and was part of the squad which won the Aviva Premiership title in 2012.
The 25-year-old, who was born in Hannover, has had two stints with Newcastle Falcons – making 50 appearances for the Aviva Premiership side.
He has represented England Saxons and England Under-20s.
George Hunter has been at Scotstoun for five years, after coming through the Scottish Rugby Elite Development Programme.
The 23-year-old loosehead has made three appearances for the club and last season played for Ayr in the BT Premiership.
Props Strain and Findlay both played for Glasgow Hawks in the BT Premiership last season.
Strain signed a short-term training contract with the Warriors last September and the 27-year-old former Dalziel player previously represented Newcastle Falcons on 12 occasions.
Findlay, a 28-year-old loosehead who has also played for Dalziel, made 22 appearances for Glasgow Hawks last season.
Glasgow coach Gregor Townsend said: “We’re continuing to work hard to recruit players for the new season and we’re delighted to welcome Rory, George, Gary and Steven on board.
“Rory is an experienced midfielder, having played more than 100 games during his time with Harlequins and Newcastle Falcons.
“He played very well at stand-off at the end of last season for Newcastle and he is a quality fly-half who has the physicality and rugby ability to also play elsewhere in the backline.
“George, Gary and Steven also join us on short-term deals and they will have an opportunity to compete for places in the front-row at the start of the season.”