The 28-year-old midfielder joins the Barclays Premier League clubfor an undisclosed fee on an initial six-month deal, which couldpotentially see him stay until the summer of 2014.
Wandsworth-born Sidwell said: 'I'm delighted my move to Fulham hasbeen finalised, and I'm looking forward to training with the squad andhelping the club make steady progress up the table in the second halfof the season.'
Sidwell, who had also interested Wolves before undergoing a medicalwith West Ham, joined Villa from Chelsea in 2008 after initially makingan impact in the top flight with Reading.
Home comforts: London-born Sidwell has moved back nearer to his family
He continued on Fulham's official website: 'I'd also like to thank (chief executive) Jez Moxey, and (manager) Mick McCarthy in particular, at Wolves for being so understanding in my desire to return to London and to play for Fulham.'
Fulham boss Mark Hughes added: 'He is a player whose career I have followed for a while now, and there was a deal in place to bring him in prior to when I arrived.
'At that time I just didn't think it was the moment to make it happen because I was new to the club.
'But he has been in my thoughts ever since, and when the opportunity to sign him in the January transfer window presented itself we moved quickly knowing there was a possibility he might go somewhere else.
'His intention was that he always wanted to come to Fulham - this was his first choice and we are delighted to have him on board.
'He is a young man who wants to get his career back on track and start playing football again. He has a good reputation in the game and is well admired.
'On the pitch he can get from box to box, he works tirelessly, is good on the ball and can also get you a goal. He wants to be part of what we are doing here - and because of that he will do well for us.'
Sidwell will not figure in the FA Cup third round match against League One side Peterborough at Craven Cottage.
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Explore more:People: Mick McCarthy, Mark Hughes Places: London