The experienced tight-head prop played for English Premiership side Saracens 158 times between 2009 and 2017. During that spell he won the Champions Cup twice and the English Premiership three times.
The 37-year-old, who has played 31 Champions Cup matches during an illustrious career, goes straight into the Warriors Heineken Champions Cup squad ahead of Sunday's opening game against his former side, Saracens at Scotstoun.
He arrived in Glasgow yesterday and started training with his new teammates at a training camp in Largs this morning.
"It all happened very quickly - within three days I'm here, so I'm excited to play in the Heineken Champions Cup and Guinness PRO14 this season.
"It's exciting that my first game could be against my former club Saracens - you couldn't write the script if you tried!
"I've heard the matchday experience at Scotstoun is fantastic, the crowd really gets behind the team, they're vocal and they're loud.
"Glasgow Warriors play a really expansive and physical game, which is great and I've only heard good things about the club from former players."
Glasgow Warriors Head Coach, Dave Rennie added: "It's great that we've been able to obtain someone of Petrus' experience at such short notice.
"He has played rugby at the highest level, is a good man and a really solid set piece operator.
"With Zander (Fagerson) and Siua (Halanukonuka) injured he brings some much needed depth at tight-head."