In 1979, Jett was in England pursuing a solo career. She recorded three songs there with the Sex Pistols' Paul Cook and Steve Jones, one of which was an early version of Arrows' "I Love Rock 'n' Roll". This version appears on the 1993 compilation album Flashback. Later that year, she returned to Los Angeles, where she began fulfilling an obligation of the Runaways to complete a film that was loosely based on the band's career entitled We're All Crazee Now! Three actresses stood in for the departed band members, including Rainbeaux Smith, who was also a rock drummer. While working on the project, Jett met songwriter and producer Kenny Laguna, who was hired by Toby Mamis to help Jett with writing some tracks for the film. They became friends and decided to work together. Jett relocated to Long Beach, New York, where Laguna was based. The plug was pulled on the project halfway through shooting after Jett fell ill, but in 1984, after she became famous, producers looked for a way to use the footage from the incomplete film. Parts of the original footage of Jett were eventually used in another project, an underground film called DuBeat-Eo, which was produced by Alan Sacks, but not commercially released.
With Laguna's assistance, Jett formed the Blackhearts. Laguna recounted, "I told Joanie to forget the band and support herself on the advance money. There was enough for her but not for a band. She said she had to have a band. And I believe to this day that it was the Blackhearts, that concept, that made Joan Jett." She placed an ad in the LA Weekly stating that she was "looking for three good men". John Doe of X sat in on bass for the auditions held at S.I.R. studios in Los Angeles. He mentioned a local bass player, Gary Ryan, who had recently been crashing on his couch. Ryan was born Gary Moss, and adopted his stage name upon joining the Blackhearts in 1979, in part to cover for the fact that he was only 15 at the time. Ryan was part of the Los Angeles punk scene and had played bass with local artists Top Jimmy and Rik L. Rik. He had been a fan of the Runaways and Jett for years. Jett recognized him at the audition and he was in. Ryan in turn recommended guitarist Eric Ambel, who was also at the time part of Rik L. Rik. The final addition to the original Blackhearts was drummer Danny "Furious" O'Brien, formerly of the San Francisco band the Avengers. This lineup played several gigs at the Golden Bear, in Huntington Beach, California, and the Whisky a Go Go in Hollywood before embarking on their first European tour, which consisted of an extensive tour of the Netherlands and a few key shows in England, including the Marquee in London.