TORONTO - Shawn Mendes pocketed four awards and stole the hearts of countless screaming teenagers at the iHeartRadio MMVAs on Sunday.

The Pickering, Ont.-raised singer was the recurring star of the Toronto street party. He opened and closed the show with performances of his songs “Lost in Japan” and “In My Blood,” but also turned up several more times to dish out love to his Canadian fans.

“This is home,” he said while clutching the MMVA for artist of the year.

“This means the absolute world to me.”

The pop singer picked up three other MMVAs, best pop artist and two awards voted by viewers - fan fave artist and video.

He also snuck onto the stage to accept one that wasn't his own.

IN PHOTOS: 2018 iHeartRadio MMVAs

Mendes left the crowd screaming with delight after he revealed himself underneath the disguise of another musical star, electronic producer Marshmello. The mysterious Top 40 DJ has kept himself anonymous for several years, so seeing Mendes mugging in the costume was a total shock.

“Woah, what happened there?” Mendes jokingly exclaimed as he dove into a fake acceptance speech.

Host Awkwafina opened the show dressed in striped pyjamas and delivered a spirited monologue that proved she hasn't changed much, despite starring in “Crazy Rich Asians,” which sits atop the North American box-office for a second week.

“I'm still that girl with the voice of a pro-wrestler and the body of a Pikachu,” the vibrant YouTuber told the crowd.

But she also wanted to clarify one thing for viewers who might be seeing her on TV for the first time.

“I am not Sandra Oh, all right?” she said, referring to the Ottawa-born actress who's Emmy-nominated for her turn in “Killing Eve.”

“That's another Asian woman - and she's great.”

Megan Trainor was another early performer, with a charged mash-up of her new song “No Excuses” alongside other fan favourites that included the Top 40 hit “Me Too.”

Model and TV host Tyra Banks showered Trainor with compliments after the performance.

“What I love about Megan Trainor is she keeps it beautiful and she keeps it real,” Banks said.

Awards handed out included best collaboration, which went to Bebe Rexha and Florida Georgia Line for the summer hit “Meant To Be.”

Rexha raced onto the stage to accept the award, pausing for a moment to let out a hearty scream.

Other awards were doled out on the red carpet before the official show started.

Electronic duo Elijah Woods and Jamie Fine, who were victorious in the CTV singing competition “The Launch,” were selected as best new Canadian artist or group.

Viral pop singer Halsey was awarded the “artist for change” recognition for her work on mental health awareness and suicide prevention.

Toronto-based filmmaker Karena Evans picked up the best director award for the music video “God's Plan,” which featured Toronto rapper Drake giving away money to surprised strangers in Miami.

Other performers included 98 Degrees, the 1990s boy band whose member Nick Lachey admitted he was feeling some major nostalgia as he walked the red carpet. The group chatted with personality Ed the Sock at the 1999 MMVAs.

“We did an interview with a sock puppet with a cigar in its mouth - there's nothing more unique than that,” Lachey said Sunday evening.

“This is a celebration of music, the fans, and it's great to be back and part of the energy here.”

Other presenters included Michael Jackson's son Prince, who took a moment to urge the audience to get behind causes that matter to them, such as education reform and ending homelessness.

“You're never too young to speak out and stand up,” he said.