The 24-year-old centre will earn $2.6 million next season, $3.3 million in 2018-19 and $3.4 million in 2019-20.
Pageau had eight playoff goals last spring as the Senators reached the Eastern Conference final. He had 12 goals and 21 assists over 82 regular-season games.
"As an organization we are thrilled that we got this contract done," Senators general manager Pierre Dorion said on a conference call. "Arbitration is definitely a path we did not want to go down with Jean-Gabriel, especially the way he’s performed over the course of the last few seasons. He showed that he was definitely deserving of this contract.
"Any player that has a history of raising his game, whether it was in junior playoffs or (AHL) playoffs or NHL playoffs, I think you have to give credit for what he’s accomplished. We’re really happy to have him on board for the next three years."
Over 251 career regular-season games, Pageau has 101 points (45 goals, 56 assists) and 71 penalty minutes.
Pageau had four goals — including the game-winner — in Ottawa’s 6-5 double-overtime win over the New York Rangers in Game 2 of their conference semifinal. The Ottawa native, who grew up in nearby Gatineau, Que., has 16 points (12-4) in 35 career playoff games.
"We’ve always had a good relationship with Pierre, with (former GM) Bryan (Murray) before, with the team," Pageau said. "They always knew that I wanted to stay with the team. I take pride (in playing) for the Senators. So obviously I think that helped get the deal done. I’m happy … to be here for the next three years."
Pageau was drafted by the Senators in the fourth round (96th overall) of the 2011 NHL draft.