Yet in real life, the wife and mother of two wants to make it very clear she's no exhibitionist on her own time.
"Sex is absolutely what helps sell this movie, which is fine with me," Alba tells Entertainment Weekly in its latest cover story. "I'm also playing a character when people are taking pictures of me. That's what I do, but it is not who I am."
In fact, Alba, 33, makes it clear she's really, really different than the sex symbol label that has been attached to her over the years.
''I never slept my way through Hollywood, so I never felt like I compromised. Apparently people do it, I didn't. I felt like I never compromised myself because I'm a prude. I don't know. I grew up Catholic. In my head I'm always thinking, 'Oh God, can my grandma see this?,' " she says.
Alba says the sex symbol label was confusing at first, since it's always been at odds with the way she views herself.
"I'm kind of a prude, and I didn't really understand," she says. "They would always ask me provocative questions about my sexuality, my this or that."
"Sometimes I would lie and say something that wasn't true to make myself seem more interesting than I was," says Alba, who runs a multimillion-dollar Honest Company while being a hands-on parent to daughters Honor, 6 next month, and Haven, 2 ½, with husband Cash Warren. "I mean, I didn't even know how to walk in heels until I went to the Golden Globes for the first time."