The 33 year old has spent the last two seasons with MK Dons, having initially moved to the club on loan from Newcastle United in January 2012.
Smith began his career with Leeds United, turning out for them over two-hundred times before moving to Manchester United following the Yorkshire side’s relegation to the Championship.
In three years at Old Trafford, he won the Premier League title and the League Cup, while he added to his collection of silverware by landing the second-tier title with Newcastle in 2010.
He won nineteen caps for England between 2001 and 2007, scoring his only international goal on his debut – a friendly against Portugal at Villa Park.