While two celebrities becoming engaged is far from shocking, what confused many on the Internet was the fact that Grande and Davidson had only been dating for a few weeks before reports were leaked.
The One Last Time singer was seen sporting a large diamond ring during a performance in Los Angeles on 2 June.
Responding to a fan that tweeted: "I hope he knows he is marrying us as well", the singer tweeted: "HAHAHAHAHAHAHA HE'S BEEN BRIEFED".
Grande and Davidson, a comedian and actor best known for his sketches on Saturday Night Live, both recently ended previous relationships.
News of the USA singer dating the comedian came less than two weeks after she announced she had broken up with rapper Mac Miller.
Previously, Grande had been dating rapper Mac Miller.
Page Six confirmed on Monday that the fast-moving couple made plans to tie the knot after a whirlwind romance that has included Grande-inspired tattoos and plenty of PDA.
The 24-year-old also told her friend, fellow pop star Camila Cabello - who often calls her "wife" - that they "need to talk".