Grande, despite telling fans that she had no special guests planned for her second Coachella show on Sunday, introduced Bieber onstage to perform his song "Sorry."
"This is my first time performing here in two years, and I had to get my groove back, my swag back, you know what I'm saying," Bieber told the crowd before teasing that his next album is coming soon.
"Thank you @ArianaGrande. Thank you @coachella. That felt right. Love you," Bieber said on Twitter Monday.
Grande also performed "God Is a Woman," "Side to Side," "Bang Bang," "No Tears Left to Cry" and "Thank U, Next" among other songs. The pop star previously shared the stage with 'NSYNC -- minus Justin Timberlake, Nicki Minaj, Diddy and Mase at her first Coachella concert last weekend.
Bieber's last album, titled Purpose, was released in November 2015. He previously said in March that he was going to be taking a break from music to focus on personal issues.
Grande and Bieber recently appeared together in Lil Dicky's new pro-environment single "Earth." The track, which is helping to raise funds for Leonardo DiCaprio's pro-environment foundation, also features Snoop Dogg, Adam Levine, Shawn Mendes, Sia, Miley Cyrus, Lil Jon, Kate Perry, Ed Sheeran and many others.