Farinacci was drafted 76th overall by the Arizona Coyotes in the 2019 NHL Entry Draft. He committed to play college ice hockey at Harvard University starting in the 2019–20 season.
On April 12, 2023, it was announced that Farinacci would not sign with the Coyotes, and intended to test the free agent market. He became a highly coveted collegiate free agent, and ultimately signed a two-year entry level contract with the Bruins on August 16, 2023.