The Iran international made 30 appearances for Bolton Wanderers before joining the Cottagers last summer.
However, the 25-year-old's first-team chances at Craven Cottage have been extremely limited and he has made only one start for Roy Hodgson's side this term.
He told the Tykes' official website: "I was unfortunate to get an injury that kept me out of the Fulham side when a first-team place was on the cards.
"Although I'm now match-fit, with Fulham going well in the Premier League, it's difficult to break back into the first team.
"I need games at this stage of the season and had no hesitation in coming to Barnsley where I know I can do the midfield job that the club needs."
Barnsley signed Coventry City striker Michael Mifsud on loan earlier on transfer deadline day.