Hoffman did not take the fast track to NHL prominence.

He was cut by both his hometown club, Kitchener of the Ontario Hockey League, and Gatineau of the Quebec Major Junior Hockey League before landing with Drummondville of the QMJHL and scoring 19 goals and 36 points in 43 games during the 2007-08 season.

Bypassed in the 2008 NHL Draft, Hoffman had a tryout with Philadelphia Flyers that fall but did not make the team. The next season, though, he increased his production, scoring 52 goals and 92 points in 62 games and helping Drummondville reach the Memorial Cup.

It was enough to convince the Ottawa Senators to select the then-19-year-old in the fifth round (No. 130) of the 2009 NHL Draft, but he would remain in the QMJHL the following season, being named the league MVP with 46 goals in 56 games for Saint John.

He turned pro in 2010, but progress was slow. Between 2010 and 2014, Hoffman he played mostly for Binghamton in the American Hockey League, though he did make 28 appearances for the Senators.

In 2014-15 he became a regular with Ottawa and responded with a team-high 27 goals in 79 games. Having established himself as a reliable scorer, Hoffman was rewarded on July 27, 2016, when he and the Senators avoided salary arbitration by agreeing on a four-year contract.