Mae was born in Los Angeles, California, the daughter of Pat Musick, a voice artist, and Jeff Whitman, a personal manager and set construction co-ordinator. She started her career with a voice over for a Tyson Chicken commercial, a role her mother had also auditioned for. During this time, Whitman attended Ribét Academy, a private preparatory school, in Los Angeles. She later transferred to Whitefish Bay High School.

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 youngest daughter, Casey, in the movie.

In the movie Independence Day she played the President's daughter; she also played George Clooney's daughter Maggie in One Fine Day and Sandra Bullock's daughter Bernice in Hope Floats.

She guest starred in the episode "The One Where Rachel Quits" of the sitcom Friends in 1996.

During several guest appearances from 1998 until 2001, Whitman played the role of Chloe Madison on JAG. Chloe was Sarah 'Mac' Mackenzie's (Catherine Bell) Little Sister, through the Big Sister, Little Sister program. In 2001 and 2002, Whitman starred in the Fox Family series State of Grace.

Whitman was the voice of Navajo Wynonna "Winnie" Whitefeather for Focus on the Family's The Last Chance Detectives audio cases (2004).

Whitman appeared in the 2006 series Thief for FX Networks, playing the stepdaughter of Nick Atwater (Andre Braugher). 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 made several high profile guest appearances in 2006 and 2007, including a stint on ABC's Grey's Anatomy as Heather. She also appeared on Desperate Housewives as an unscrupulous friend of Julie.

Whitman was initially cast in the 2007 series remake of The Bionic Woman, playing the deaf younger sister of the title character. On June 27, 2007, TV Guide reported that Whitman was being replaced in the role of Jaime's sister, and Lucy Hale was cast as Whitman's replacement the following July. An NBC spokesperson confirmed this, stating, "The decision was purely creatively driven. It is very common to change storylines, characters, actors after the initial pilot is shot." The sister character's hearing was restored after this recasting at the request of an NBC executive. She also appeared in the season nine episode "Streetwise" of Law and Order: Special Victims Unit, as an on-the-street-mother who adopts street children forming a homeless family.

Whitman was the voiceover for Katara of the Water Tribe in the animated show Avatar: The Last Airbender, and previously Rose in American Dragon: Jake Long. She has appeared most recently in the HBO series In Treatment as Rosie.