[13] Having grown up listening to American bands, she discovered Australian singer-songwriters Darren Hanlon and Dan Kelly, who inspired her to start writing songs.

[17] Around this time Barnett featured on a track by Melbourne singer-songwriter Giles Field called "I Can't Hear You, We're Breaking Up" which was released in late 2011.

[18] Between 2011 and 2013, Barnett was a member of Australian psych-country band Immigrant Union, a musical project founded by Brent DeBoer (of The Dandy Warhols) and Bob Harrow.

Along with sharing vocal duties, Barnett predominantly played slide guitar and is on the band's second studio album, Anyway.

In 2013, Barnett played lead guitar on Jen Cloher's third studio album, In Blood Memory, which was also released on Milk!

[21][22] It was named the album of the week by Stereogum[23] The track "History Eraser" was nominated for the APRA Song of the Year.

Marathon Artists and House Anxiety partnered with Mom + Pop Music for the U.S. release of The Double EP in 2014.

Records released a compilation EP, A Pair of Pears (with Shadows), on 10" white vinyl in September 2014, following a crowd-sourcing campaign in July that year.

The EP included a Barnett track, "Pickles from the Jar", the song was voted in at number 51 in Triple J's Hottest 100 for 2014.

[26] On 30 January 2015, Barnett released details on her upcoming full-length album, recorded in April 2014 with Burke Reid, along with two singles, "Pedestrian at Best" and "Depreston", and accompanying music videos.

Records (Australia),[27] and Mom + Pop Music (US) on 23 March 2015,[28] and was accompanied by tours in the UK and Europe, America, and Australasia.

[12][36][37] In August 2015, Barnett's UK label, Marathon Artists, in partnership with Mom + Pop Music and Milk!

[38] Billboards and posters bearing the song's title went up in London, New York, Los Angeles, Melbourne and Sydney.

[39] The campaign garnered a lot of interest online and across social media and culminated in a surprise busking gig in Camden, London.

"Over Everything" initially sparked the pair's collaboration, after Philadelphia-based Vile wrote the song with the Melbourne-based Barnett's voice in mind.

The duo was backed by the Sea Lice, a band featuring Janet Weiss (Sleater-Kinney, Wild Flag), Rob Laakso (The Violators, Swirlies, Mice Parade), Stella Mozgawa (Warpaint), and Katie Harkin (Sky Larkin, touring member of Sleater-Kinney and Wild Beasts).

[47][48] On 12 February 2018, Barnett teased a new album on her social media accounts, featuring her trying out various musical instruments with the clip ending with the tagline "Tell Me How You Really Feel".

[49] Barnett released the singles "Nameless, Faceless", "Need A Little Time", "City Looks Pretty", and "Sunday Roast" from her sophomore solo album, which was launched at a private function at Sydney's Lansdowne Hotel in April 2018 and emceed by ex–The Go-Betweens Lindy Morrison.

[9] On 3 July 2022, Barnett supported the Rolling Stones at their concert at Hyde Park in London, UK.

[55] In December 2020, NME reported that a documentary titled Anonymous Club exploring "the inner life of the notoriously shy [Barnett] amidst her significant rise to fame" was in the works, after receiving $2.5 million in funding from Screen Australia.

[56] Anonymous Club was directed by Danny Cohen,[57] who had collaborated with Barnett on several of her music videos previously,[58] and was executive produced by Sue Maslin and her company Film Art Media.

Barnett's song "Pickles from the Jar" also details their relationship, and Cloher is mentioned in the first line of "Dead Fox".