Sheeran, 23, who appeared at the MMVAs for his fourth straight year and his first as host, was also named the most buzzworthy international artist at the ceremony held in Toronto, Canada.
"This is my fourth year and I've never won one. I feel like it's just because I'm presenting," he said while accepting the trophy for best international artist.
Sheeran sang "Photograph," a single from his "x" album, accompanied by a string quartet and pulsating drumming.
25-year-old R&B star The Weeknd, also known as Abel Tesfaye, beat out Arcade Fire, Kiesza, Grimes and Majid Jordan in the best video competition.
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The Weeknd was also named the most buzzworthy Canadan artist, while Sam Pilling earned the best director trophy for his work on the "Often" video.
Only seven awards were handed out during the two-hour telecast on the CTV, Much Music and other cable channels, with Hailee Steinfeld, Brody Jenner, Adam Lambert, Lights, Cody Simpson and Gigi Hadid among the presenters.
A big impromptu moment at the MMVAs came when Toronto's own Drake made a surprise appearance to help accept the best hip-hop video award for P Reign's "DnF", which featured the superstar rapper and Future, and was directed by Drake and Davin Black.
"My brother Drizzy Drake is in the building. That's my brother for life," a surprised Reign said after Drake dropped in for the prize-giving and unleashed a wall of screaming and shouting from his hometown fans.