Farabee was selected by the Philadelphia Flyers with the No. 14 pick in the 2018 NHL Draft after two successful seasons with the USA Hockey National Team Development Program Under-18 team.

In 2017-18, the forward was captain of the NTDP U-18 team and was second on the team in scoring with 76 points (33 goals, 43 assists) in 62 games. He had eight points (four goals, four assists) in seven games to help the United States finish second at the 2018 IIHF World Under-18 Championship.

In 2018-19 as a freshman at Boston University, he won the Hockey East and NCAA rookie of the year awards after he led his team with 36 points (17 goals, 19 assists) in 37 games.

Farabee signed a three-year, entry-level contract with the Flyers on March 25, 2019, and after a strong training camp was the final forward cut from the roster prior to the 2019-20 season. He was assigned to Lehigh Valley of the American Hockey League but was recalled Oct. 20, and made his NHL debut against the Vegas Golden Knights the next day, scoring his first NHL point in his second game, with an assist at the Chicago Blackhawks on Oct. 24, and scored his first League goal at the New Jersey Devils on Nov. 1.

Farabee had 201 points (90 goals, 111 assists) in 383 games for the Flyers before getting traded to the Calgary Flames with Morgan Frost on Jan. 30, 2025, for Andrei Kuzmenko, Jakob Pelletier, a second-round pick in the 2025 NHL Draft and a seventh-round pick in the 2028 NHL Draft, on Jan. 30, 2025.