Katherine Langford was born in Perth, Australia on April 29th, 1996.
She began voice lessons in 2005, and received classical, jazz, and contemporary vocal training.
She attended Perth Modern School, a public school for the gifted located in Subiaco, Western Australia, where she was a nationally ranked swimmer.
Early on in her high school career, Langford was interested in medicine and politics, in addition to musical theater.
However, in 2012, when Langford was 16, she attended Lady Gaga's concert, the Born This Way Ball, which inspired her to learn how to play the piano and quit the swim team.
For her final year at Perth, Langford stopped swimming and switched her focus to music and performance.
Langford appeared in the school's production of Hotel Sorrento in 2013 and graduated in 2014 with a diploma of musical theater.
After graduating high school, Langford signed an agent and began enrolling in acting classes and workshops in Perth.
From 2014 to 2015, Langford studied at the Principal Academy of Dance & Theatre Arts, majoring in Music Theatre.
While there, she appeared in a production of Godspell, where she played Morgan.
She was then one of five selected to participate in the National Institute of Dramatic Arts (NIDA) Advanced Actors Residency in 2015.
Also in 2015, she trained at Nicholson's Academy of Screen Acting.
During this time, she also portrayed the role of Peron's mistress in the 2015 production of EVITA at the Koorliny Arts Centre in Perth.
In late 2015, Langford was offered a position in the Bachelor of Arts program in Acting at the Western Australian Academy of Performing Arts (WAAPA) and intended to begin studies in 2016. However, she never enrolled and instead pursued professional roles.
Langford first appeared in several small independent films in 2015, including Misguided, Imperfect Quadrant, and Daughters. Langford portrayed the lead character, Scarlett, in Daughters, which debuted at the 2016 Cannes Film Festival. In 2016, after declining the offer from WAAPA, Langford auditioned for Will, a TV series centered on the young life of William Shakespeare. She did not get the role, which was instead given to Olivia DeJonge.
Langford auditioned for the role in 13 Reasons Why over Skype and had only 10 days to get an O-1 visa as she had not worked in the United States before. She has received critical acclaim for her portrayal of the American high school student Hannah Baker in 13 Reasons Why. Langford researched the role, speaking with a representative of the sexual assault awareness campaign "It's On Us" and a psychiatrist who specialises in adolescence. In December 2016, she signed with the William Morris Endeavor agency.
Langford will star in the upcoming 2018 adaptation of the coming-of-age novel, Simon vs. the Homo Sapiens Agenda by Becky Albertalli, as Leah.
