Selected by Melbourne with pick 17 in the 2008 national draft, Blease spent five years at the Demons.
The speedy midfielder played a total of 33 games for the Demons and booted 25 goals.
Blease was nominated for the AFL Rising Star in both 2011 and 2012, the latter a stand-out year in which he played 16 games for 19 goals.
Geelong football manager Neil Balme said Blease is a welcome addition to the club’s midfield group.
“We see Sam as a player who can bring pace as well as a great ability in front of goal.
“We hope Sam can find more consistency in his game and become a regular face in our side next year."
Blease will begin training at Simonds Stadium later this month.