Dempsey moved back to America this summer to join Seattle Sounders after spending six years in the Premier League with Fulham and then Tottenham.
The USA international netted 50 goals for Fulham in his first spell with the club although the Whites fans felt some bitterness towards their former star when he left for Spurs.
The 30 year old has undergone a medical at the Cottagers’ training ground and will officially join on January 1 and could make his debut against West Ham on new years’ day.
Dempsey will join on a two month loan while the MLS off season continues before re-joining Seattle for their pre-season in March.
Fellow MLS stars Robbie Keane and Landan Donovan have been linked with a short team loan move to back to the Premier League but Dempsey is the first to make the switch.