The Scotland international, 25, has worked previously with Worcester director of rugby Alan Solomons during his time in charge of Edinburgh.
McCallum arrived at Scotstoun in July 2021 to bolster the club's front-row options ahead of the start of the United Rugby Championship season, making his Glasgow Warriors debut against Ulster in the opening match of the campaign.
Capable on either side of the scrum, McCallum has made three appearances for the club to date and was also named in the Scotland squad for the Autumn Nations Series.
"I've absolutely loved my time at Glasgow," McCallum told glasgowwarriors.org.
"Everyone here has been top class, from the coaches to the players - coming down the M8 is obviously never an easy one, but they've taken me in as one of their own! It's been a fantastic six months.
"I'm excited to take on a new challenge at Worcester. The Premiership will be a new experience for me, and I'm looking forward to getting stuck in about it.
"The fans at Scotstoun have welcomed me with open arms and I want to say a massive thank you to them for their support, too. I'll definitely be back, joining them for a beer in the stands one day!"