Following Michaels' concert at the Fonda Theater in Los Angeles, California, on Monday -- during which Gomez surprised the crowd on stage to perform their song, "Anxiety" -- she and Gomez got matching tattoos backstage.
Tattoo artists London Reese and Brad Reis took to their Instagram Stories to document their time inking the pop stars. In the pics, Michaels can be seen drawing on Gomez's wrist before having the tattoo artist step in. On Reese's Story, he revealed that the women opted for "matching tatties" during the ink session.
Gomez later shared pics on her IG story about her and Michaels' new tats.
Prior to getting inked, Michaels delighted the crowd by bringing Gomez onto the stage to perform their 2019 track live for the first time. Michaels, who hugged Gomez as she came on to the stage, sported a black turtleneck and a pink-and-yellow miniskirt for the concert, while Gomez wore a gray jumpsuit and a black, lacy bra.
Both women were smiling and seemed to have a great time on stage, with Gomez even laughing it off when she flubbed a lyric. An eyewitness tells ET that, after the performance, Michaels, 25, and Gomez, 27, accidentally kissed on the lips while aiming for each other's cheeks, before Gomez apologized to the crowd for "f**king up the lyrics."
The eventful night came just one day after Michaels' '90s prom-themed birthday party, which she held ahead of her 26th birthday later this week. On Monday, Gomez shared pics from the bash, writing, "My love, my heart and my soul @juliamichaels 🖤"
"😭😭😭😭🙌🏼🙌🏼🙌🏼🙌🏼 the amount I love you is unreal," Michaels, who has co-written many of Gomez's songs, commented.
Last September, Michaels opened up to ET's Katie Krause about her friendship and working relationship with Gomez.
"She's amazing, and I think she wants to do her own thing and have her own words and her own expressions and I think that's amazing," Michaels said. "I want her to f**king flourish! Because she deserves it. She deserves everything."
"She's everything to me," Michaels added. "I wouldn't be doing this without her."
Reporting by Madison Brodsky