Paul McMullan, who has played both as a forward and a winger for the Parkhead outfit’s youth sides, has joined Ian Murray’s squad until next summer.
He spent the second half of last season at League One team Stenhousemuir, where he made 19 appearances and scored three goals.
The teenager’s temporary stay at Ochilview was a development loan which entitled him to also play for Celtic’s U20s and he was part of the team which beat Rangers 5-2 to win the Scottish Youth Cup final in May.
McMullan is the third new arrival at St Mirren this close season after midfielders Scott Agnew and Stuart Carswell were drafted in from Dumbarton and Motherwell.
He has yet to make a first-team appearance for Celtic but is now in his ninth season there and has UEFA Youth League experience against the likes of Barcelona.
McMullan will be joined in Paisley by another club-mate after Celtic agreed to provide two youth players for St Mirren’s forthcoming Championship campaign.
They played summer friendly against Dutch side Den Bosch on Wednesday – with McMullan featuring as a substitute – and have further meetings with Dukla Prague and Real Sociedad there on Saturday and next Friday.
Celtic are reported by the Daily Record to have paid an estimated £200,000 for the privilege to host matches there while the pitch is relaid at their own ground.
The agreement has caused controversy, however, after the Glasgow side removed St Mirren signs and put up their own as they set up a temporary club shop at the stadium.
Saints are understood to have asked Celtic to tone down their rebranding after receiving complaints from their own supporters.