On July 1, 2010, Stepan signed his first professional contract with the New York Rangers, forgoing his junior and senior years at Wisconsin. In Fall 2010, having attended the Rangers' training camp and playing for the team during the pre-season, Stepan made the transition from Wisconsin to the NHL. He scored a hat trick in his first NHL game on October 9, 2010, against Ryan Miller of the Buffalo Sabres, becoming the first rookie in Rangers history to do so, en route to a 6–3 victory. He is only the fourth player in NHL history to have scored a hat-trick in his debut, joining Alex Smart of the Montreal Canadiens (January 14, 1943), Réal Cloutier of the Quebec Nordiques (October 10, 1979) and Fabian Brunnström of the Dallas Stars (October 15, 2008). Auston Matthews of the Toronto Maple Leafs later accomplished the feat with four goals (October 12, 2016). Stepan was selected as a member of the 2011 NHL All Star roster on January 11, 2011, and performed in the NHL SuperSkills competition on January 29, 2011.
