Haggerty played two seasons with the USA Hockey National Team Development Program and won a gold medal with Team USA at the 2011 IIHF World U18 Championships. Before turning professional, Haggerty attended the Rensselaer Polytechnic Institute where he played three seasons (2011–14) of NCAA Division I hockey with the RPI Engineers, registering 47 goals, 37 assists, 84 points, and 102 penalty minutes in 106 games.