Wu was born in Berkeley, California, and raised in Orinda, California. His parents, Diana, a college professor, and George Wu, a retired engineer, are natives of Shanghai, China. His father immigrated to the United States after the communist revolution in China in 1949, and met his mother in New York, where she was a student. After marrying, they settled in California. Wu has two older sisters, Greta and Gloria.
Wu developed an interest in martial arts when he saw Jet Li in The Shaolin Temple and Donnie Yen in Iron Monkey, and consequently began studying wushu at age 11. His childhood role model was Jackie Chan, a man who now considers Wu "like a son." Wu attended the Head-Royce School in Oakland, California and later majored in architecture with Tony Salas at the University of Oregon. While there, he founded the University of Oregon Wushu Club in 1994 and served as the team's first coach. During this time, Wu also took film classes and frequented local theaters, and came to enjoy the works of filmmakers like Akira Kurosawa and Luc Besson, whom he describes as "men of vision."
Following graduation, Wu traveled in 1997 to Hong Kong to witness the handover of Hong Kong, with no intention of taking on a movie career. At the suggestion of his sister, Wu began modeling. Four months later, film director Yonfan, after seeing Wu featured in a clothing ad at a railway station, approached Wu about starring in an upcoming movie.
Despite his inability at the time to speak Hong Kong Cantonese or read Chinese, Wu successfully completed his first movie, Yonfan's Bishonen in 1998. Still today, when he receives a Cantonese script, his assistant reads the entire piece, while he is making notes on the pronunciation. The day after Bishonen wrapped, Wu was offered the leading role in Mabel Cheung's City of Glass (for which Wu was nominated as best new actor at the 18th Hong Kong Film Awards), and later, a supporting part in Young and Dangerous: The Prequel, from Andrew Lau's gangster film series. Around this time, Wu met superstar Jackie Chan at a restaurant opening, and was quickly signed to Chan's JC Group with agent Willie Chan. Wu's breakthrough performance came in 1999 with his role in Benny Chan's Gen-X Cops. He followed this success with roles in a variety of movies including big-budget thriller Purple Storm, art-house production Peony Pavilion, and the extremely successful Love Undercover. In 2001, Wu received criticism from the Hong Kong media for sexual scenes with Suki Kwan in Cop on a Mission, but Wu says that same criticism attracted the attention of directors and the film represented a turning point in the types of roles he chose in the future.
Wu's first experience in film production came with his starring role in Julian Lee's 2003 film, Night Corridor. Due to budgetary constraints, Wu also participated in the search for funding for, and distribution of, the film, and recruited Jun Kung to create the soundtrack. Though Night Corridor dealt with "risky" themes, Wu felt he had less reliance on image than many of his pop-star actor peers, and he was nominated for best actor at Taiwan's 40th Golden Horse Film Awards for his effort. During 2003, Wu also took part as producer and creative director on "MTV's Whatever Things!", a "Jackass"-styled program aired in Asia, also featuring Sam Lee, Josie Ho, Terence Yin, and other celebrities. Also during 2003, Wu took part in a stage production of The Happy Prince at the Edward Lam Dance Theater as part of the Hong Kong Arts Festival, during which he recited a 16-minute monologue in Cantonese, learned entirely from pinyin. In 2005, Wu was nominated as best actor at the 24th Hong Kong Film Awards for his role in Derek Yee's One Nite in Mongkok, and as best supporting actor for New Police Story. At the 41st Golden Horse Film Awards, Wu won the award for best supporting actor for New Police Story. The win came as a surprise to him, because he "didn't think that much" of his performance in the film.
In 2005, Chinese media began to report that Wu had formed a boy band, Alive, with Terence Yin, Andrew Lin, and Conroy Chan. Wu and his bandmates posted information, updates, personal thoughts (including slamming Hong Kong Disneyland, for which they were spokespersons), and the band's music, at their official website. In 2006, Wu made his writing and directorial debut with The Heavenly Kings, which chronicles Alive's formation and exploits. After the film's release, however, it was revealed that The Heavenly Kings was actually a mockumentary of the Hong Kong pop music industry, and Alive was constructed purely as a vehicle to make the movie; the film's characters represented only 10–15% of their real-life counterparts and much of the footage blurred the line between fiction and reality. Wu admitted his own singing voice "sucked really bad," and the band had their voices digitally enhanced for its music, to prove that "it's easy to fake it." Despite some backlash from the media over being intentionally fed false information in the movie about illegal downloads of the band's music, Wu won the best new director award at the 26th Hong Kong Film Awards, an achievement he called "a group effort."
In November 2015, he began starring as Sunny on the AMC action series Into the Badlands, for which he also serves as executive producer.
In 2016, he portrayed via motion capture and voiced Gul'dan, the central antagonist of the action fantasy film, Warcraft ,based upon the popular video game series by Blizzard.
In April 2007, Wu re-launched his band's old website, AliveNotDead.com, with Terence Yin and RottenTomatoes.com founders Patrick Lee and Stephen Wang, as a place for filmmakers, musicians, and other artists to collaborate, receive exposure, network, and interact with fans. He continues his modeling career as spokesperson for a variety of products such as Seiko and L'Oréal. Wu posed for the charity photography album SuperStars by Leslie Kee, and performed on rapper Jin's song, "HK Superstar." Wu is an investor in Racks MDB Shanghai, which opened in 2008.
Wu maintains residences in Hong Kong, Shanghai, and Beijing. He continues to actively train in wushu as well as other martial arts.
On April 6, 2010, Wu married Lisa S. in South Africa. Their daughter was born in June 2013.