2010-11: Ben Harpur played forward and defense for the Niagara Falls Canucks midget AAA team. He had 18 points with 111 penalty minutes in 43 games. Harpur participated in the OMHA Under-17 Program of Excellence Camp in Guelph in May and was selected by Guelph in the third round (43rd overall) of the 2011 OHL Priority Draft.
2011-12: Harpur made his OHL debut as a 16-year-old and skated in 34 games for Guelph in his first season. He had a three point game (1 goal, 2 assists) in a 10-2 win over Erie in his second game but had just 1 assist the rest of the year while seeing limited time. He finished the year +1 with 22 penalty minutes. The Storm finished fourth in the Midwest Division but Harpur did not see any action in the six-game playoff series with Plymouth.
2012-13: Harpur skated in 67 of 68 games for Guelph in his second season. He scored 3 goals with 12 assists and was +14 with 59 penalty minutes. Guelph was once again fourth in the Midwest Division despite finishing with 16 more points than in 2011-12. Harpur had no points and was -2 with 2 penalty minutes in the five-game playoff series with Kitchener. He was ranked 101st amongst North American skaters in Central Scouting’s final rankings and was select by Ottawa in the fourth round (108th overall) of the 2013 NHL Draft.
2013-14: Harpur attended his first training camp with the Senators before returning to eventual OHL champion Guelph. In 67 regular season games for the Storm he scored 3 goals with 13 assists and was +34 with 69 penalty minutes. Dominating the OHL and winning 52 of 68 games in the regular season in finishing first in the Midwest Division, Guelph defeated North Bay in the OHL finals to reach the Memorial Cup. Harpur scored 1 goal with 4 assists and was +22 with 12 penalty minutes in 20 playoff games. The Storm reached the Memorial Cup championship game, falling to WHL champion Edmonton. Harpur was +2 with no points and 4 penalty minutes in four Memorial Cup games.
2014-15: Harpur returned to the OHL as a 19-year-old, beginning the season with Guelph before being obtained by the Barrie Colts in a mid-season trade. He scored 4 goals with 16 assists and was +10 with 40 penalty minutes in 28 games for the Storm. Harpur scored 1 goal with 10 assists and had an even plus/minus with 22 penalty minutes in 29 regular season games for Barrie. The Colts finished first in the Central Division and reached the second round in the playoffs. Harpur scored 2 goals with 4 assists and was +9 with 6 penalty minutes in nine playoff games. He skated in one game for the OHL All-Stars in the Subway Series against Russia, finishing -1 with no points and 15 penalty minutes. Harpur signed a three-year entry-level contract with the Ottawa Senators in November 2014.
Harpur will skate for Ottawa's rookie tournament team in September and compete for a roster spot in training camp. Still eligible to return to the OHL for an overage season in 2015-16, he will likely begin his pro career in the AHL with Senators' affiliate Binghamton.