The 32-year-old striker has returned to England following a spell in the MLS with Toronto, and hopes to hit the ground running under caretaker Blackpool manager Barry Ferguson.
Blackpool become Earnshaw's sixth British club, with the forward having been a regular scorer for Cardiff City, West Brom, Norwich City and Nottingham Forest either side of an unproductive spell at Derby County.
"This is a great opportunity for me to play some games and give the fans something to cheer about before the end of the season," Earnshaw told Blackpool's official website.
"Mentally I feel really fresh because I've been dying to go, so signing here is going to be exciting.
"I'm hoping I can come here and give the fans some goals and somersaults, give them what I've given to every other team."
