Fulham seal deal for Sidwell
"He is a player whose career I have followed for a while and there was a deal in place to bring him in prior to when I arrived (in the close season)," Fulham manager Mark Hughes said in a statement.
"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."
Former Chelsea and Reading player Sidwell, 28, has been on the fringes of the Villa side in recent months.