Whitman was born in Los Angeles, California, and is the daughter of Pat Musick, a voice artist (who voiced Haru's mother), and Greg Whitman, a personal manager and set construction coordinator. She started her career with a voice-over for a Tyson Chicken commercial, a role her mother had also auditioned for.
At the age of four, Whitman made her film debut, acting alongside Meg Ryan in When a Man Loves a Woman. She played Ryan's daughter in the movie. She had a role in Independence Day as President Whitmore's daughter Patricia, George Clooney's daughter in One Fine Day, and Sandra Bullock's daughter in Hope Floats. She guest-starred in the episode "The One Where Rachel Quits" of the sitcom Friends in 1996. During this time, Whitman attended Ribét Academy, a private preparatory school in Los Angeles.
As a more mature actress, Whitman joined the cast of Thief for FX Networks, playing the stepdaughter of Nick Atwater (Andre Braugher). She played the part of Roxanne "Roxie" Richter (Evil Ex #4) in the film Scott Pilgrim vs. the World. She was also featured in several video games, playing the role of Yuffie Kisaragi in the Square-Enix/Disney video game Kingdom Hearts II as well as an appearance in the third-person shooter RPG Dirge of Cerberus: Final Fantasy VII.
Whitman had previously worked with Dante Basco, Zuko's voice actor, on American Dragon: Jake Long. On the show, Basco voiced the protagonist, Jake Long, who had a crush on Rose, voiced by Whitman, throughout the series, who turned out to be serving the main antagonist, Huntsman. This is the reverse of the case on Avatar, where Basco voiced the antagonist character. By the middle of Season 2, the final season, Rose becomes one of the hero's allies, just as Zuko did in season 3 of Avatar.