2010-11: Brendan Harms played for the Portage Terriers of the MJHL. In 59 games for that club, he scored 28 goals and added 35 assists for 63 points. In 17 playoff games, Harms scored 4 goals and 9 assists for 13 points in the Terriers' run to the first of two consecutive MJHL championships. Harms also played for the Canada Western at the World U17 Hockey Challenge, scoring 1 goal and 1 assist in 5 games. He was chosen in the sixth round, 80th overall, of the 2011 USHL Entry Draft by the Fargo Force. Harms committed to Bemidji State University beginning in the 2013-14 season.
2011-12: Harms played for the Portage Terriers again this season, scoring 22 goals and adding 35 assists for 57 points in 42 games. He followed that up with 10-goal, 10-assist performance in 15 playoff games as the Terriers won their second consecutive MJHL championship.
2012-13: Harms played for the Fargo Force of the USHL this season, appearing in 64 games for that team. He scored 25 goals and added 45 assists for 67 points while racking up a +33 rating. In 12 playoff games for the Force, Harms scored 5 goals and added 5 assists for 10 points in the Force's run to the USHL championship series, a series they lost to the 2013 Clark Cup champion Dubuque Fighting Saints. Harms took part in the 2013 USHL Top Prospects Game. He will attend BSU in the fall of 2013. Harms was ranked 93rd by CSS among North American skaters eligible for the 2013 NHL Draft.