Selected by New Jersey with the No. 6 pick in the 2015 NHL Draft, Zacha has 76 points (29 goals, 47 assists) in 201 regular-season games and no points in five Stanley Cup Playoff games.
"We are happy to have finalized this three-year agreement as Pavel is an important part of our team," Devils general manager Ray Shero said. "He has established himself as someone who can play in any situation and we are looking forward to his continued growth as a player."
Zacha said he was impressed with the offseason moves the Devils made, which included selecting center Jack Hughes with the No. 1 pick in the 2019 NHL Draft, trading for defenseman P.K. Subban and signing forward Wayne Simmonds.
"It was really exciting, we've got a lot of skilled players, tough players to play against," Zacha said. "I was just excited to see the direction it's going and to meet all the new guys."