Lucy Liu - an agent of change

She has been a Charlie's Angel, an assassin and a snake – and in real life Lucy Liu is into politics. Lesley O'Toole meets her

Lucy Liu has been breaking barriers since the time she won her first acting job – as the lead in a university production of Alice's Adventures in Wonderland.

Immersed in studying for her degree in Asian languages and culture, this brainy New Yorker (she speaks six languages) harboured no professional aspirations in the acting arena (though she'd long been painting and making collages for fun). Alice provided her with an epiphany of sorts, one she says her parents still aren't convinced about. It has made this 39-year-old the most successful Asian-American actress in the US.

"The way I see it, you have one shot in your life to make a decision about what you want to do. My parents had been very focused on education, which I can absolutely appreciate, but if I wasn't going to pursue that, then I wasn't going to do it at all. As far as acting goes, I just went for it."

Watch the Kung Fu Panda trailer

Liu's new film, DreamWorks' animated Kung Fu Panda, already a massive hit in America, is her most high-profile since the pair of Charlie's Angels films in which she starred alongside Cameron Diaz and Drew Barrymore in 2000 and 2003. Fittingly for the daughter of Chinese immigrants (her father was a civil engineer, her mother a biochemist before the family moved to the US), the film is set in China. But Liu says that played no part in her wanting to be involved.

"Not really. Of course it was nice to be a part of a film of which the backdrop is China. That was exciting and I know my family's going to really enjoy that. I am a first-generation American so I grew up with all that history and culture. I guess this is one of those fantastic things I can cross off my list, but then I've done a lot of different projects that I've been fortunate to have been a part of that had originally not had the idea of someone being Asian in it. In this case I really don't think I was cast because I'm Asian because we also have Dustin Hoffman, Angelina Jolie and Jack Black, and the last I saw they weren't Asian."

Black is the title character, Po, whose father wants him to take over the running of the family's restaurant. Po wants to be a kung-fu master. The film's theme is accidentally encapsulated in a comment Liu (who plays a kung-fu expert snake, Viper) makes about her heritage: "I am who I am and I bring that everywhere."

Liu lives in New York but meets me at Beverly Hills' Pretty Woman hotel. She's wearing big black beads round her neck, which almost perfectly match her long, near-black hair, and her skin is luminous. Though she always appears on the right end of best dressed lists, Liu insists she's no glamour puss. "It would be jeans and T-shirts all the way if it wasn't for my stylist giving me stuff to wear."

Voicing an animated creature proved much more compelling for Liu than its solitary nature did to Hoffman. "I know he didn't like it. I loved it. I love that you're not being put through hair and make-up and wardrobe. This way you just have to focus on your intention for where you want to take this character."

Though Liu says she was swept up in the film when she saw it for the first time ("I was so enjoying it I completely forgot why I was there"), there's no mistaking the luscious lilt of her voice.

"They did want us to keep our voices fairly close to what they normally sound like otherwise it would be very cartoony. I find that TV and movies are completely different for voiceovers. In TV, it's usually completely scripted, but you can play with the voice a lot more. For Futurama I was playing myself so they wanted me to sound like myself. But in The Simpsons, I was playing a communist so I could have more fun with that, King of the Hill the same kind of thing. "

Despite Liu's eclectic career, she realises she is in a small minority of Asian-American actors who have initiated what she terms "colour-blind casting. It's really taking a while but I do think it's becoming more acceptable to cast Asians in roles that weren't originally slated for someone who is Asian, which is so great."

While the lack of ethnic roles in Hollywood remains no joke for the likes of Liu, she is pragmatic about the ones available to her and seemingly content to make the best of what's on offer. The role that made her famous was the bitchy lawyer Ling Foo in Ally McBeal. But her race has also proved advantageous. In Quentin Tarantino's Kill Bill she played a Japanese assassin and she was a Chinese princess in Shanghai Noon opposite Jackie Chan.

When not working as an actor for hire, Liu has plenty to keep her occupied. She is a longtime ambassador for Unicef and she donates proceeds from her art sales to the charity. Liu also likes to have her own semi-political voice inveigle its way into her films when she can. She starred in the 2005 film 3 Needles to help publicise Chinese and Thai hill tribes' curious beliefs about eliminating HIV and Aids, and she executive-produced the 2006 documentary Freedom's Fury about the 1956 Hungarian Revolution.

We chat about the Beijing Olympics and she confesses she's not likely to watch much as she doesn't have a TV. "I'm staying in a kind of propped-up trailer right now." This almost certainly means she's crashing at a friend's place when she could be staying at whichever LA hotel du jour she fancied. A friend who once accompanied Liu on a promotional trip told me his charge was "lovely and totally low maintenance". It appears to show.

Liu mentions a telling, regular happening in her life. Whenever she is recognised, no one calls her Lucy. "It's always Lucy Liu." She'll take it. She'd just prefer Lucy.

'Kung Fu Panda' opens on 4 July