General manager Jeff Gorton announced the signing of the 2015 second-round draft pick on Thursday.
Gropp has skated in 32 games with the Seattle Thunderbirds of the Western Hockey League (WHL) this season, collecting 18 goals and 14 assists. The 19-year-old leads the Thunderbirds in goals, ranks fourth on the team in points, and ranks fifth in assists.
The 6-foot-2, 190-pounder has 66 goals and 66 assists in 158 career WHL games over three seasons.
Gropp was the 41st pick overall in the draft.