Mitchell's most recent concert was in 2002.

Mitchell last performed a full concert when she took the stage at the Wiltern in Los Angeles in 2002, as reported by The Guardian. In the time since, the singer-songwriter has occasionally performed live, but only a song or two here and there. For instance, earlier this year, she sang two songs—"Big Yellow Taxi" and "The Circle Game"—with artists who took part in the tribute when she was honored as the MusiCares Person of the Year in April, according to People.

Mitchell's most recent album, Shine, was released in 2007. She won the Grammy for Best Instrumental Pop Performance in 2008 for the song "One Week Last Summer."

She faced a major health setback.

In 2015, Mitchell suffered a brain aneurysm, which left her needing physical therapy to learn how to walk and talk again.

"...I couldn’t walk. I had to learn how again. I couldn’t talk," she told The Guardian in 2020. She compared it to a serious illness she survived when she was young. "Polio didn’t grab me like that, but the aneurysm took away a lot more, really," Mitchell continued. "Took away my speech and my ability to walk. And, you know, I got my speech back quickly, but the walking I’m still struggling with. But I mean, I’m a fighter. I’ve got Irish blood! [long laugh] So you know, I knew, 'Here I go again, another battle.'"

For more celebrity news delivered right to your inbox, sign up for our daily newsletter.

Mitchell surprised fans during Carlile's set.

Newport Folk Festival attendees had no idea they were going to see Mitchell perform before the singer joined Carlile's set. While the two artists sang together, Carlile mostly sat back, giving Mitchell time to shine. The younger musician is a huge fan of Mitchell's and in 2021, performed her 1971 album Blue in full with Mitchell in attendance.

Mitchell sang many of her most famous songs, including "Both Sides Now," "Big Yellow Taxi," and "A Case of You," as well as covers of the songs "Summertime" and "Why Do Fools Fall in Love." She also played the electric guitar solo from "Just Like This Train."

Mitchell last performed at the Newport Folk Festival in 1969.

Many other guests joined in.

In addition to Carlile, Mitchell was also joined on stage by musicians including Wynonna Judd, Blake Mills, Marcus Mumford, Taylor Goldsmith, and more, according to Pitchfork. The Guardian reports that at one point Carlile said, "I just realized, Joni’s the least nervous person up here."

The live performance mimicked the private jam sessions Mitchell has held her in her home in recent years, which have come to be known as "Joni Jams," according to The Guardian. Guests at those exclusive events have included Elton John, Herbie Hancock, and Bonnie Raitt.

READ THIS NEXT: The First Sign of the Disease That Ended Linda Ronstadt's Performing Career.

The set was Carlile's vision.

In an interview with CBS Mornings, Carlile explained that, initially, Mitchell would spend Joni Jams enjoying the other musicians rather than singing along. It was one instance when Mitchell started to participate herself that Carlile imagined what it would be like to recreate the moment in Newport.

"I knew she’d do it at Newport. I can’t really say how I knew it. I just pictured her out there," Carlile said. "I pictured the water and the fort and the boats.”

As for Mitchell, she told CBS Mornings that she wasn't nervous to be performing live again.

“No, I’ve never been nervous about being in front of an audience," she said. "But I wanted to be good and I wasn’t sure that I could be, but I didn’t sound too bad tonight."