The deal is worth $1.9 million in Year 1 and $2.3 million in Year 2.
"We're relieved to have this settled before going to arbitration," general manager Don Waddell said. "Brock was an important part of what we accomplished last season and we're happy to have him as part of our group moving forward."
McGinn's arbitration hearing was scheduled for Saturday - the first official day of meetings.
The 25-year-old winger contributed 10 goals and 26 points in 82 games last season, adding six points in 15 playoff contests.
It's common for the team and player to reach an agreement before arbitration. Last summer, 40 of 44 players ultimately signed with their respective teams before reaching their hearing dates. This summer, McGinn marks the 13th player to sign before their scheduled meeting.