The 31-year-old moves to France from Penrith Panthers and is a veteran of two World Cups, having earned 19 caps for the Kiwis.
Whare scored 40 tries in 155 NRL appearances for Manly Sea Eagles and Penrith.
Catalans coach Steve McNamara said: “Dean will be a great addition to our squad.
“He is an outstanding professional with great ethics, he will bring real quality and class to our attack whilst he is also a player who loves the tough defensive side of the game.”
Whare said: “I am very excited for the new opportunity to be joining the Catalans Dragons.
“I am looking forward to meeting the team and embracing the French culture. There are some exciting times ahead and I can’t wait to start.”