Scodelario was born Kaya Rose Humphrey on 13 March 1992 in Haywards Heath, West Sussex. Her mother, Katia Scodelario, is a Brazilian woman who moved to England in 1990; Scodelario's surname comes from her mother's Italian grandfather. Her father, Roger Humphrey (died 22 November 2010), was English. Scodelario's parents divorced when she was a child and she was raised in London by her mother, subsequently adopting her surname and becoming fluent in Portuguese.
In 2007, at the age of 14 and with no prior acting experience, Scodelario was cast in the first series of Skins as Effy Stonem. At the auditions, Scodelario became discouraged as she felt she was too young. However, a producer told her to stay and she was asked to read for the part. While Scodelario's role in the first series had minimal speaking lines, her character developed considerably in the series during 2008. She eventually became the central character in the 2009 and 2010 series after the cast had been replaced with a new generation of characters. This made Effy one of the only characters to appear from series 1 right through to series 4 of Skins. Filming began in July and Scodelario revealed that 18 November 2009 had been her last day of filming the series and that she would miss being on the show.
Scodelario left after the fourth series, making way for the third generation of characters. Her performance was praised by critics, and she was nominated twice in the category for Best Actress at the TV Quick Awards in 2009 and 2010. In the episode titled "Fire", one of the three parts of the seventh (and final) season of Skins, Scodelario reprised the role of Effy. It is a two-part rendition of her life as an adult, lasting a total of two hours. She claims "Fire" is "more like a movie" and that she could relate, as both Scodelario and her character, Effy, struggled to change from a teenager into an adult.
Scodelario made her film debut in the science fiction-thriller film Moon, which premiered at the 2009 Sundance Film Festival, receiving positive reviews. In her second film Shank, she plays a teenager called Tasha. The film was released on 26 March 2010. In addition, she appeared in the 2010 remake of the Clash of the Titans as Peshet.
She appears in the music videos for "Stay Too Long", "She Said", "Love Goes Down", and "Writing's on the Wall" by English musician Plan B. She can also be seen in the music video for "Old Isleworth" by The Ruskins and Robbie Williams' 2012 single, "Candy".
In April 2010, Scodelario confirmed her casting as Cathy in an adaptation of Wuthering Heights directed by Andrea Arnold. Principal photography started in September and concluded in November 2010. The film premiered at the Venice Film Festival in September 2011 to generally positive reviews, and Scodelario was even hailed as a "heart-wrenching revelation". Wuthering Heights also appeared at several other international film festivals, including the 2011 Toronto International Film Festival, London Film Festival, and the 2012 Sundance Film Festival. The film was released in the UK on 11 November.
In 2011, she signed on to play "Sally Weaver" in a British thriller, Twenty8k. Filming lasted six weeks during April and May 2011. The film was released in September 2012. In late June, Scodelario announced that she has signed on to star in Now Is Good with Dakota Fanning. The film is based on Jenny Downham's novel, Before I Die, about a teenage girl with leukaemia who creates a list of things to do before she dies. She portrays Zoey, the protagonist's best friend. Production was shot in seven weeks in July and August. In late September 2011, Scodelario filmed a television serial for BBC One, True Love, an improvised series comprising five stand-alone episodes, each covering a different love-related dilemma. She is cast in the third storyline as Karen, the love interest of her teacher, who is portrayed by Billie Piper. The episode aired on 19 June 2012.
In January 2012, Scodelario filmed her first American film, The Truth About Emanuel, in Los Angeles. She stars as the title character, Emanuel, a troubled 17-year-old girl who babysits her new neighbour Linda's "baby", which is actually a very lifelike doll. Limited Release on 10 January 2014. While visiting her boyfriend on the set of Spike Island in April, Scodelario filmed a cameo appearance for the film. She also participated in an advertising campaign for Korean jewellery brand J. Estina. In 2013 she starred in the four-part Channel 4 drama series Southcliffe, which tells the story of a fictional English town devastated by a spate of shootings, exploring the tragedy through the eyes of a journalist and those close to the victims.
She signed on to the film franchise The Maze Runner in April 2013 as the lead female character, Teresa, in the first film, released in September 2014, and its sequel, Maze Runner: The Scorch Trials, released in September 2015. She starred in lead roles in the home-invasion thriller, Tiger House, and the film adaptation of The Moon and the Sun, which was expected for a 2015 release. She also had a starring role in the sequel Pirates of the Caribbean: Dead Men Tell No Tales, which was released May 26, 2017.
Scodelario reprised the role of Teresa in Maze Runner: The Death Cure, based on the novel of the same name by author James Dashner. The film was set for release in 17 February 2017; however, after her co-star Dylan O'Brien was injured on-set, the film was pushed back to February 9, 2018.
Scodelario was previously signed with Models 1 and has modeled for various magazines, including Teen Vogue, Nylon, Instyle UK, Elle UK, Dazed & Confused, Vogue, and i-D.
Scodelario dated her Skins co-star Jack O'Connell for about a year before splitting up in June 2009, though they remain good friends. She was in a relationship with Elliott Tittensor from late 2009 to early 2014. During their relationship, she supported Tittensor after his arrest for an incident where he hit someone while driving in an uninsured car.
In April 2014 during the filming of The King's Daughter (formerly known as The Moon and the Sun), Scodelario began dating her co-star, Benjamin Walker. They became engaged on 28 December 2014, and married in December 2015. They have a son born in November 2016.
From 2008 to 2010, Scodelario lived alone in a flat in North London, stating her belief that it is important for women to be "independent and strong". Scodelario suffers from dyslexia and tweeted in 2010, "Watching an interesting doc on BBC Three about dyslexia, something that I have struggled with my whole life. It really affected my self-esteem."
She was voted 13th in the UK edition of FHM's 100 World's Sexiest Women 2010.