The duo then set to work on a full-length album, balancing schoolwork with the recording sessions. The Big Black & the Blue was released in 2010, and was followed by a request from Jack White to record a single at his Third Man Studios, which resulted in their cover of Buffy Sainte-Marie's "Universal Soldier." They struck up a friendship with Conor Oberst and appeared live with Bright Eyes on tour, before they entered the studio with the band's guitarist Mike Mogis for The Lion's Roar, which arrived in early 2012. The lead single "Emmylou" was listed by Rolling Stone as the tenth best single of the year, and the LP debuted at number one in Sweden. It also charted in several other countries, including the U.S., where it reached number 65 on the Billboard 200 and the Top Five of the Americana/folk chart.

The sisters' creative relationship with Oberst was cemented in 2014 when they sang backing vocals on his solo album Upside-Down Mountain, and that same year the duo released Stay Gold, their first album on the major-label Columbia. It hit number one in Sweden and Norway, and charted in the Top 25 in several European countries, the U.S., Canada, Australia, and New Zealand. Stay Gold went on to win Album of the Year at Sweden's Grammis. After two years of touring, festivals, and international TV appearances (including a cover of Simon & Garfunkel's "America" for Late Show with David Letterman), First Aid Kit headed to Portland, Oregon to record their fourth LP. Featuring production by Tucker Martine (My Morning Jacket, the Decemberists) and backing musicians such as R.E.M.'s Peter Buck, Wilco's Glen Kotche, and Midlake's McKenzie Smith, the resulting Ruins was informed by the aftermath of Klara's broken engagement. It arrived via Columbia in early 2018. ~ Andrew Leahey & Scott Kerr, Rovi