An eyewitness tells ET that Grande and Alvarez were "all over each other all night." While she did mingle with friends, she always wandered back to share more PDA with her man.
Grande's good pal and former Victorious co-star, Liz Gillies, also joined the "Dangerous Woman" singer for the celebratory party, which went on until Grande, Alvarez and Gillies left the club at 5:15 a.m ET.
Gillies also snapped a selfie with Grande after her friend’s hosting gig, which she posted to Instagram with the caption, "Post-SNL with my talented little dingus last night."
The 22-year-old actress' hosting appearance on SNL received a ton of love from fans and critics, who praised the Grande for her comedic timing as well as her two live performances.
Grande took to Twitter after the show to thank the long-running sketch series for having her own, writing, "Last night was an absolute dream come true. forever grateful @nbcsnl."
In one of the episode's highlights, Grande got to show off her impressive talent at musical impersonations when she imitated the vocal stylings of artists like Britney Spears, Rhianna, Celine Dion and Whitney Houston in a skit titled "Tidal." Check out the epic sketch in the video below.