Duffy is ranked as the 33rd overall commit and second-best pocket-passer in the class on the ESPN 300.
"I feel great about my decision," he said, according to 247Sports.com's Chris Nee. "There are a lot of reasons why I chose Florida State, but the biggest is just the overall feeling I had on my visits and the direction the program is going in moving forward."
The Bradenton, Florida, native chose the Seminoles over offers from several schools, including Miami, LSU, and USC.
Duffy is the second four-star signal-caller to join Florida State's 2022 class after Nicco Marchiol also committed to the Seminoles in January.