Sportsnet's Elliotte Friedman reports the contract is worth $1.7 million.
"Anthony is a dynamic and highly skilled player who is capable of being a dependable offensive contributor for our team" said Panthers general manager Bill Zito. "He possesses tremendous speed and goal-scoring ability and earned an opportunity to be named an NHL All-Star last season. We're excited to welcome Anthony and look forward to what he can add to our team."
Duclair, 25, is coming off one of the best statistical years of his career, recording 40 points (23 goals, 17 assists) in 66 games with the Ottawa Senators last season.
The Panthers will be Duclair's fourth team after spending time with the Senators, Arizona Coyotes and New York Rangers.
Duclair was one of several notable unrestricted free agents left available on the open market prior to the Panthers signing him. The likes of ex-Florida forward Mike Hoffman, former Nashville Predator Mikael Granlund and defenceman Travis Hamonic are among the remaining top UFAs as the 2020-21 season draws closer.