Everett's documentary on Sir Richard Francis Burton (1821–1890) in which he retraces the travels of Burton through countries such as India and Egypt, aired on the BBC in 2008. In the documentary, titled The Victorian Sex Explorer, Everett explores the life of a man who investigated a male brothel frequented by British Soldiers in Bombay in disguise; who introduced The Koran, One Thousand And One Nights and the Kama Sutra in their first English translations; who travelled to the city of Mecca, and kissed the Holy Stone of Kaaba in disguise as an Arab; and was able to converse in more than 20 languages. Everett explained in 2008: "I've been interested in him for years. So many contradictions. Such a riveting, showbusiness character. The godfather of the sexual revolution."

For the 21st century, Everett has decided to write again. He has been a Vanity Fair contributing Editor, has written for The Guardian and wrote a film screenplay on Playwright Oscar Wilde's final years, for which he sought funding.

Everett's break came in 1981 at the Greenwich Theatre and later West End production of Another Country, playing a gay schoolboy opposite Kenneth Branagh. His first film was the Academy Award-winning short A Shocking Accident (1982), directed by James Scott and based on a Graham Greene story. This was followed by a film version of Another Country in 1984 with Cary Elwes and Colin Firth. Following on with Dance With a Stranger (1985), Everett began to develop a promising film career until he co-starred with Bob Dylan in the huge flop Hearts of Fire (1987). Around the same time, Everett recorded and released an album of pop songs entitled Generation of Loneliness.

In 1989, Everett moved to Paris, writing a novel, Hello, Darling, Are You Working?, and coming out as gay, a disclosure which he has said may well have damaged his career. Returning to the public eye in The Comfort of Strangers (1990), several films of variable success followed. The Italian comics character Dylan Dog, created by Tiziano Sclavi in 1986, is graphically inspired by him. Everett, in turn, appeared in an adaptation based on Sclavi's novel, Dellamorte Dellamore (1994). In 1995 he released a second novel, The Hairdressers of St. Tropez.

Everett has performed in many other prominent films, including The Madness of King George (1994), Shakespeare in Love (1998), Inspector Gadget (1999), A Midsummer Night's Dream (1999), The Next Best Thing (2000), The Chronicles of Narnia: The Lion, the Witch and the Wardrobe (2005), Stardust (2007) and the Shrek sequels. He co-starred with Eva Green in Tim Burton's film Miss Peregrine's Home for Peculiar Children (2016).

His career was revitalised by his award-winning performance in My Best Friend's Wedding (1997), playing Julia Roberts's character's gay friend, followed by Madonna's character's best friend in The Next Best Thing (2000). (Everett was a backup vocalist on her cover of "American Pie", which is on the film's soundtrack). Around the same time, he starred as the villainous Sanford Scolex/Dr. Claw in Disney's Inspector Gadget (also 1999) with Matthew Broderick.

Despite being managed by the largely successful pop svengali Simon Napier-Bell (who had steered Wham! to prominence), the public didn't take to his change in direction. The shift was short-lived, and he only returned to pop indirectly by providing backing vocals for his friend Madonna many years later, on her cover of "American Pie" and on the track "They Can't Take That Away from Me" on Robbie Williams' Swing When You're Winning in 2001.

In 2006, as a homeowner in the central London area of Bloomsbury, Everett actively supported a campaign to prevent the establishment of a local Starbucks branch and referred to the global chain as a "cancer". Everett protested alongside one thousand other residents and the group compiled a signed petition.

In May 2007, he delivered one of the eulogies at the funeral of fashion Director Isabella Blow, his friend since they were teenagers, who had committed suicide. He asked as part of his speech: “Have you gotten what you wanted, Issie? Life was a relationship that you rejected.” During this time he also voiced the nefarious, but handsome mama's boy Prince Charming in the first two Shrek sequels.

Everett then returned to his acting roots, appearing in several theatre productions: his Broadway debut in 2009 at the Shubert Theatre received positive critical reviews; he performed in a Noël Coward play, Blithe Spirit, starring alongside Angela Lansbury, Christine Ebersole and Jayne Atkinson, under the direction of Michael Blakemore. and he was expected to tour several Italian cities during the 2008–09 winter season in another Coward play, Private Lives (performed in Italian, which he speaks fluently)—playing Elyot to Italian Actress Asia Argento's Amanda—but the production was cancelled.

In addition to his two memoirs and the screenplay for the Wilde biopic, Everett has written several books, such as The Hairdressers of St. Tropez. In November 2010, Everett stated: "... I'm busy writing a TV series called 'Boy Band,' about a boy band, and the second part of my autobiography, titled 'Goodwood, Pinewood, Hollywood and Bollywood' ..."

Everett then starred as Oscar Wilde in The Judas Kiss, a stage play which was revived at London's Hampstead Theatre beginning 6 September 2012, co-starring Freddie Fox as Bosie, and directed by Neil Armfield. The play ran at the Hampstead through 13 October 2012, toured the UK and Dublin, and then transferred to the West End at the Duke of York's Theatre on 9 January 2013 in a limited run through 6 April 2013.

During 2013, Everett, a former sex worker, worked on the production of a documentary on sex work for Channel 4 that includes the issue of criminalisation. Both during and after the filming of the documentary, Everett contributed to the discourse on prostitution legislation in the UK. In October 2013, Everett signed an open letter by the English Collective of Prostitutes and Queer Strike—alongside groups and organisations such as the Association of Trade Union Councils, Sex Worker Open University, Left Front Art – Radical Progressive Queers, Queer Resistance and Queers Against the Cuts—to oppose the adoption of the "Swedish model", whereby only the clients of sex workers, but not the sex workers themselves, are criminalised.

Everett continued his participation in the sex work legislation debate in 2014, writing a long form piece for The Guardian and appearing on the BBC One programme This Week. Everett's January Guardian article was published in the wake of police human trafficking raids in the Soho area of London and he wrote:

In 2015 it was announced that he would play the part of Philippe Achille, Marquis de Feron, the corrupt Governor of Paris, Head of the Red Guard and illegitimate brother to Louis XIII in the third series of the BBC One drama The Musketeers.

Everett won the WhatsOnStage Award for Best Actor in a Play, and was nominated for the Olivier Award for Best Actor. In 2016 the production, still starring Everett and with Charlie Rowe as Bosie, ran in North America for seven weeks in Toronto and five weeks at BAM in New York City.

In 2017 Everett appeared as a recurring character in the BBC2 comedy Quacks. He plays Dr Hendricks, the paranoid principal of the medical school.