Celtic have agreed extended deals with three first-team regulars, the club announced on their website.
Defenders Charlie Mulgrew, Adam Matthews and winger James Forrest signed extensions until 2016.
The 26-year-old Mulgrew, in his second spell at Celtic, said he was delighted to secure his future with the Scottish champions.
"It's good to get it signed and focus only on the football," the versatile international said.
The former Aberdeen and Wolves defender added: "Last year was a good one for me. I've been happy to be back."
"Things have been going well for me, so hopefully that can continue."
Celtic manager Neil Lennon revealed last week that Mulgrew was one of six players - the others being Forrest, Matthews, Gary Hooper, Thomas Rogne and Victor Wanyama - involved in talks about extending their deals.
"All the players here now understand what this club is all about and, for me, growing up as a Celtic fan, I understand fully what the fans expect here and hopefully we can deliver that," added Mulgrew.
"All the boys have a big drive and they've been here long enough to understand what the club is all about.
"It's a massive club and there is a big pressure here, week in and week out, but everybody's happy here."