James Bolton has agreed a contract extension that keeps him at St Mirren until the summer of 2025.
The defender joined the club in July 2023 after his contract expired at English Championship side Plymouth Argyle.
The 29-year-old has made 18 appearances for the Saints so far this season, starting all of the last six games.
Manager Stephen Robinson said: "James had to be patient for his chance. Our three centre-halves started the season well, but he’s been the ultimate professional and now broken into the team.
"He adds a bit of steel and I think James will keep getting better with games.
"Sometimes there is a lot of focus on bringing players in, but I think it’s just as important to retain the players that you’ve got. I think it’s a really good bit of business."