Arnold's third film was based on Emily Brontë's 1847 novel and starred Kaya Scodelario and James Howson. This is the first film that Arnold has directed which she did not write herself, though she did co-write the screenplay. Originally, the film adaptation was set to be directed by Peter Webber, who directed Girl with a Pearl Earring, but Arnold was asked to take over and gladly accepted. The film was made in 18 months, which is half the amount of time Arnold used to make Red Road and Fish Tank. Oscilloscope Laboratories picked up the North American distribution rights to the adaptation, which won Best Cinematography at the Venice Film Festival in 2011, being praised for its visuals.
After leaving school in the late 1970s, Arnold got her first TV jobs as a Dancer on shows that included Top of the Pops. She first came to prominence as an Actress and television presenter alongside Sandi Toksvig, Nick Staverson and Neil Buchanan in the 1980s children's television show No. 73. This Saturday morning show on ITV, in which she played Dawn Lodge, had a similar premise to that of The Kumars at No. 42 in the way that the show was part sitcom, part chat show and based at a domestic residence. In addition to these parts, the show had the usual mix of music, competitions and cartoons that was in keeping to the formula of British Saturday morning children's TV of the 1980s. After a couple of years of experience in front of the camera, Arnold realised, "Television was great fun and I went along for the ride, but I never felt that comfortable in front of the camera".
In 1988 No. 73 had morphed into 7T3, with the set being moved from the Maidstone house (in fact in TVS studios in Kent) to that of a theme park. This revamp would only last the season, but Arnold would be seen for another two years in the same timeslot as part of the Motormouth presenting team. In 1990 she presented and wrote for the environmental awareness show for teens, A Beetle Called Derek. This also featured Benjamin Zephaniah and gave exposure to The Yes/No People of Stomp fame.
After retiring from her career as a television presenter, Arnold studied directing at the AFI Conservatory in Los Angeles and trained in screenwriting at the PAL Labs in Kent. Her early short films included Milk (1998) and Dog (2001). She won the Academy Award for Best Live Action Short Film for Wasp, in 2004.
Initially released in 2003, Wasp was a short (26 minutes) written and directed by Arnold. Released in 2003, it stars Natalie Press as a struggling single mother determined not to let her four young children prove an obstacle in the pursuit of igniting a relationship with an old friend (Danny Dyer). Arnold's native Dartford is the setting. The film was commissioned by the UK Film Council and the Britain's Channel 4. It won the Sundance Short Film Prize in 2005, and won Arnold an Oscar for Best Live Action Short Film
Red Road was a 2006 film that is a part of a creative series proposed by the Advance Party of Filmmakers to create three films using the same characters, all directed by different new Directors. It tells the story of a CCTV security operator who observes through her monitors a man from her past. It is named after, and partly set at, the Red Road flats in Barmulloch, Glasgow, Scotland which were the tallest residential buildings in Europe at the time they were built. It is shot largely in a Dogme 95 style, using handheld cameras and natural light.
She won the 2007 BAFTA Award for Outstanding Debut by a British Writer, Director or Producer for directing Red Road. In 2008, Arnold was reported to be directing an adaptation of Gillian Flynn's novel Sharp Objects for French production company Pathé, but the project never materialized. In 2011, she was reported to be working on a television project with Writer Danny Brocklehurst called Dirty, but this project also failed to materialize.
Fish Tank premiered in 2009 and was accepted into competition for the Palme d'Or at the Cannes Film Festival and received the Jury Prize. In its initial production, distributor Artificial Eye had acquired the UK theatrical rights, while ContentFilm International handled the worldwide sales. The film was backed by the Limelight Fund, BBC Films and the UK Film Council's New Cinema Fund. The film was shot entirely on location in the UK. Arnold was Adam Ant about shooting the film in chronological order, so that the journey of the film would make sense to new coming actor Katie Jarvis. She would only give her a day's worth of script to study so that she could take it day by day. The film originally premiered on around 45–50 screens in Britain, making them less accessible to the general public. In regards to this, Arnold said, "I definitely feel sorry more people don't get to see my films. They aren't inaccessible, and if people got the chance to see them, I know they'd like them. I wish cinema [owners] could be braver, or had more money to help them show films like mine." The film cost around $2 million to make, which is still a relatively low budget for a feature-length film. Fish Tank won many awards including the best film award at the Evening Standard Film Awards. Fish Tank was released on 11 September 2009. The film and Arnold were honoured at the 20th Annual Women in Film and TV Awards in 2010.
She was appointed Officer of the Order of the British Empire (OBE) in the 2011 New Year Honours for services to the film industry.
Arnold has been very active in working with film festivals around the world. She has been described as a "film festival regular even between films." In 2012 she was a member of the Jury for the Main Competition at the 2012 Cannes Film Festival. In 2013 she was named as a member of the jury at the 70th Venice International Film Festival. In 2014 Arnold was announced as the chair of the jury for International Critics' Week at the 2014 Cannes Film Festival. In 2016, Arnold was chosen to take part in a public conversation about her career as part of the Tribeca Film Festival's "Tribeca Talks" programme. Arnold was a jury member of the 2017 Sheffield Doc/Fest.
In September 2013, Arnold was named the New York Film Festival's inaugural "Filmmaker in Residence." As the first "Filmmaker in Residence," Arnold was responsible for "creating a template for the programme." The programme is designed to "further the goals of filmmakers at an earlier stage in the creative process." Through the programme, Arnold was given the "opportunity to focus on developing or refining new work, and participate in master classes, mentorships or cultural exchange and enrichment film programmes with the Film Society of Lincoln Center members, the film community and the public."
In 2015, it was announced that she would direct two episodes of the Amazon Studios series Transparent.
Arnold's fourth film, American Honey, revolves around a group of young adults traveling across the country selling magazine subscriptions. The film had its world premiere and competed for Palme d'Or at the 2016 Cannes Film Festival. It won Arnold her third Jury Prize. The film features a mix of both professional and non-actors, with all the non-actors being found through construction sites, parking lots, and on beaches. The lead Sasha Lane was spotted by Arnold on a beach during spring break. The film was released in the United States on 30 September 2016, and in the United Kingdom on 14 October 2016, by A24 and Focus Features respectively.
