The midfielder joined the club in August on a short-term contract and made his debut against West Bromwich Albion on the opening day of this season.
Since then, the 35-year-old has gone on to make 14 appearances for the Whites since arriving, scoring one goal against Rotherham United on Boxing Day in the Sky Bet Championship.
Bolton Wanderers manager Phil Parkinson said: “We are really pleased that the deal for Gary has been finalised. Not only does he offer experience but brings quality to the team and we are looking forward to working with him again.
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