The 25-year-old Republic of Ireland international full-back will join the London club on a three-year contract on 1st July. 'I'm happy that my transfer to Fulham has been finalised today and look forward to meeting with the rest of the team for pre-season preparations in July," Kelly told the official Fulham website. "I have spoken to the manager about plans for next season and I'm delighted to have joined a progressive club which has recently achieved its highest ever top-flight finish.
"I am also looking forward to being part of a strong squad for next season's Premier League and Europa League competitions."
Kelly joined Blues from Tottenham in the summer of 2006 and went on to make 88 appearances for Blues during his three year spell at St Andrews.
An ever-present in season 2007-08, Kelly missed most of last season through injury and was loaned to Stoke City in January although injuries restricted him to making just 6 appearances for The Potters during his four months at The Britannia Stadium.