Born December 29, 1972, in Lewisham, London, England, raised in South London by his parents, who were both school teachers, Law joined the National Youth Music Theatre at age 13, where he acted in such productions as Joseph and the Technicolor Dreamcoat. He left school at age 16 after winning a part as a teenage runaway on the British television soap opera Families. Over the next several years, Law won parts on stage, in a touring production of Pygmalion and The Fastest Clock in the Universe in London (both 1992), and on TV in both Britain and the U.S. In 1994, Law made his film debut, in the poorly received British film Shopping; the film also featured Law’s future wife, Sadie Frost, an actress best known for her appearance in Bram Stoker’s Dracula (1992). Law initially found a greater measure of success on stage than on screen. He starred in the London production of Les Parents Terribles in 1995, and became the only member of the cast who was invited to reprise his role in the hit Broadway version of the play, Indiscretions. Law earned a Tony Award nomination for Featured Actor for his starring role—complete with a much-talked-about nude scene—opposite Kathleen Turner, as a son involved in an incestuous relationship with his mother.

In 1997, he had important supporting roles in three major American films: in the futuristic thriller Gattaca, he played a genetically-perfect man crippled in an accident; in both Midnight in the Garden of Good and Evil, directed by Clint Eastwood, and Wilde, he played dangerously tempting objects of homosexual desire. Though all three films did mediocre business, Law received praise for his magnetic screen presence and, inevitably, his sultry good looks. Several more disappointments followed, including the little-seen I Love You, I Love You Not (1997), co-starring Claire Danes, Music From Another Room (1998), and The Wisdom of Crocodiles (1998, released in the U.S. in 2000). In 1999, Law’s production company, Natural Nylon—which he co-founded with Frost and friends and fellow actors Jonny Lee Miller, Ewan McGregor, and Sean Pertwee—released its first feature, the unabashedly bizarre eXistenZ, co-starring Law and Jennifer Jason Leigh. Later that year, Law won raves—and an Academy Award nomination for Best Supporting Actor—for his role as Dickie Greenleaf, the carefree playboy at the center of a chilling tale of murderous desire in The Talented Mr. Ripley.

In addition to his work in film, Law continued his work on stage, appearing in the London production of ’Tis Pity She’s a Whore in 1999. In 2001, he starred with Ed Harris and Joseph Fiennes in Enemy at the Gates, a drama set during World War II. That summer, Law played a mechanical love god named "Gigolo Joe" in Steven Spielberg's long-awaited science fiction opus A.I.: Artificial Intelligence, costarring Haley Joel Osment. Also starred in science-fiction thriller The World of Tomorrow costarring Gwyneth Paltrow. Law married Sadie Frost in 1997 and have four children: a son Rafferty, a second son Finley (whom she has from a previous marriage), a daughter Iris born in October 2000, and a third son Rudy born in September 2002. The couple lives in London.