Callahan, 22, spent the last four seasons at Providence College, serving as the captain for each of the previous three seasons. The 6-foot-2, 196-pound defenseman appeared in 136 career games with the Friars, recording 13 goals and 53 assists for 66 points and a plus-24 rating.
Prior to attending Providence, the Franklin, Massachusetts native played in 60 games in the USHL with the Bloomington Thunder, Central Illinois Flying Aces and the Youngstown Phantoms. Over two seasons, Callahan recorded three goals and 15 assists for 18 points and a plus-three rating.
Callahan was originally selected by the Arizona Coyotes in the fifth round (142nd overall) of the 2018 NHL Entry Draft.