The former Edinburgh player initially joined Saints on loan in 2023 on a season long but made it a permanent move for the 2024/25 campaign.
Scottish-qualified through his father who hails from Ayr, Savala made the move from Australia to Edinburgh in 2020.
In March 2023, Savala was called up to the Scotland international squad for the final round of the Six Nations Championship.
Comfortable across the back-line, Savala scored three tries in 15 appearances for the Saints since his move to the Gallagher Premiership side.
Savala began his rugby journey in rugby league, starting out in the Sydney Roosters academy system before switching to the 15-a-side code.
"I'm really excited to make the move to Glasgow," Savala told glasgowwarriors.org.
"I've enjoyed the last couple of seasons down at Northampton as part of a really competitive group and I feel like I've developed a lot, and having seen the success of Glasgow from afar, it looks like another group that I cannot wait to be a part of.
"I know a few of the boys from my time in Edinburgh and in Scotland training camps, so I'm looking forward to reconnecting with them and getting stuck in with the attacking brand of rugby that the club have been playing in recent seasons.
"I had a chat with Sione [Tuipulotu], and having tasted success with the 2024 title, it's clear that everyone at the club is keen to build on that success and keep on pushing.
"Glasgow have always been a team that like to attack, no matter when the opportunity arises, and that's a philosophy that really excites me and aligns with how I like to play the game. I pride myself on being able to fill whatever role the team requires of me and I want to do my bit to help this team succeed.
"I've had a few run-outs at Scotstoun with Edinburgh and Northampton, so I know how much of a fortress the boys have made it - I can't wait to run out with the Warrior Nation on my side this time!"
Head Coach Franco Smith added: "We are pleased to welcome Charlie to Scotstoun this summer ahead of the new season.
"His ability to cover a range of positions across the back-line is an important asset to us, and his attacking intent aligns with the style of rugby that we want to play.
"We look forward to bringing him into our environment, as we continue to build for the new campaign."