The veteran midfielder became the first player from the expansion Impact to earn the league honour on Monday.
Bernier set up goals from Felipe Martins, Justin Mapp and Andrew Wenger in a 4-1 victory over the Seattle Sounders on Saturday night in the team's first game at its expanded and revamped stadium. The club started the season playing indoors at Olympic Stadium.
The Brossard, Que., native, one of only two local players on the squad along with defender Carl Ouimette, signed with the Impact after nine seasons with various European clubs. He had begun his pro career with Montreal in lower leagues.
Bernier recently regained his spot in the starting 11 after spending several games on the bench and has played his best soccer of the season. He has two goals and leads the club with four assists.
Bernier stormed off the practice field when he learned he would not start the team's home opener in April, but otherwise took the demotion quietly and worked his way back to the first 11.
Coach Jesse Marsch said Bernier, one of his most talented midfielders, showed character.
"From the beginning, I told him he would be an important piece, because of the experience he has, because he's from here, and because of the position he plays," Marsch said. "It's been a bit of an adjustment for him to understand what this league is like and that's normal.
"He's handled himself in tough moments extremely well, at the highest level of any player I've ever been around. That shows you what kind of man he is. Now when it's time to step on the field and contribute, he's ready to go."
Bernier said the award came from a team effort.
"Winning brings good things," he said. "The chemistry and cohesion on the team is getting better every game."
The Impact left Monday for Los Angeles where they will face Chivas USA on Wednesday night. The teams have identical 4-7-3 records.
Not on the flight was central defender Matteo Ferrari, who injured a quadriceps muscle in his right thigh while jumping for a high ball in front of Seattle goalkeeper Bryan Meredith. He was replaced by veteran Shavar Thomas in the 33rd minute.
"Every time we've called on Shavar in difficult moments he's risen to the challenge," Marsch said of the former Jamaica international.
Ferrari was to have an MRI exam to determine the extent of the injury. The Italian defender wrote on Twitter over the weekend that the injury appears to be serious.
Also, forward Bernardo Corradi was walking gingerly on crutches after twisting his left knee during practice. He was unable to go on the road trip.
"He just got tangled a bit, we're hopeful that it's nothing big," Marsch said.
Andrew Wenger is expected to start a second game in a row at striker.
Marsch does not expect to make changes, other than Ferrari.
The starting 11 should have Donovan Ricketts in goal, Zarek Valentin, Nelson Rivas, Thomas and Jeb Brovsky on defence, Bernier, Collen Warner, Davy Arnaud, Felipe Martins and Mapp in midfield, with Wenger up front.