The "God is a Woman" singer let her signature ponytail down for the night, opting for flowing brunette locks instead.
Davidson, meanwhile, kept it casual with a long-sleeve white tee, black track trousers and Adidas sneakers. Tellingly, there was also a letter "D" whacked on the end of "AG".
Grande and Davidson announced their engagement earlier this summer after dating for a few weeks. After shouting out her fellow nominees, she turned the attention to her loyal Camilizers, telling them, "The relationship that I have with you guys is a forever thing".
Joined onstage by a diverse group of 50 female backup dancers, the pop goddess opened the set by recreating The Last Supper by Leonardo da Vinci, while seated at a long table.
Despite receiving some flack from fans, Grande even named a song after the comedian on her new album "Sweetener", which dropped days before the awards show.
The source added that Grande's performance will be "exactly what the VMAs are made of".