We wouldn't mind if Fallon trusted her to step in for him next time he goes on vacation. Enjoy all of the best moments below.
Musical Genre Challenge
Grande showed off her amazing impression (and singing) skills in this game, in which she transformed Drake's "God's Plan" into a flawless '90s diva hit (giving us major Christina Aguilera vibes), and Kendrick Lamar's "Humble" into Evanescence-esque goth-rock jam, which was by far the most impressive.
Fallon was tasked with a ska version of Ed Sheeran's "Shape of You," and a country version of Usher's "Yeah."
Grande explained why she decided to call her latest album "Sweetener."
"It's kind of about bringing light to a situation," the singer explained. "Or to someone's life or somebody else brings life to your life. Sweetening the situation."
The album, which will be released this summer, includes songs "Raindrops," "R.E.M," "The Light Is Coming," and "God Is A Woman," which is her Nonna's favorite. We suspect it's dropping on July 20th, since she teased the release date by saying, "There's only like three 20ths until the big thing."
"You do an impression that I don't know if you've done on TV before, but you were doing for me... Jennifer Coolidge," Fallon began, before asking Grande to show her impersonation of the "Legally Blonde" star.
"God, you look like the Fourth of July," Grande said in her spot-on Coolidge voice before also spitting out, "I'm taking the dog, dumbass."
"That's the type of stuff you deal with when you hang out with Ariana for two days," the late-night host explained.
For the sketch portion of the evening, Grande teamed up with Fallon to parody Bravo with a show called "NBD," where host Casey (Fallon) and his guest Cassandra (Grande) talking about things that are "no big deal."
Grande and Fallon both rocked valley girl accents, with the singer sporting a sparkly and rainbow colored getup.
"I just saw Timothee Chalamet at Au Bon Pain, no big deal," Grande explained, then name dropped about the "Queer Eye" truck being right outside.
In their first segment, "But Whatever" Cassandra bragged about how she's attending the Royal Wedding and Casey explained that how his 23andMe results told him that he's "280th in line for the throne."
In a pre-taped segment, the singer surprised fans who thought that were simply being filmed for a fan video. One by one, as the fans were recording covers of the singer's hit "One Last Time," Grande and Fallon walked in.
As expected, fans lost their minds and many broke down into tears. We're not gonna lie, though -- there were a few talented fans in the bunch that we could see dueting with Grande in the future.