During her mid-teens, she played Holly Tyler on the WB sitcom What I Like About You (2002–2006) and starred in the teen comedy films Big Fat Liar (2002) and What a Girl Wants (2003).

In her highly publicized personal life, she has struggled with mental health and other issues, and was in a conservatorship from August 2013 to March 2022.

She is the youngest of three children born to Lynn (née Organ), a dental assistant and office manager, and Rick Bynes, a dentist.

[5][6] Bynes began professionally acting at age seven, appearing in a television advertisements for Buncha Crunch candies,[7] Cut and Style Barbie, and Taco Bell.

[9] Later she attended a comedy camp at the Los Angeles Laugh Factory, at which she received advice from Richard Pryor and Arsenio Hall.

[14] In 2002, Bynes made her feature film debut in Big Fat Liar starring as Kaylee, best friend of co-star Frankie Muniz's character.

[16][17] She had a voice role in the direct-to-video film Charlotte's Web 2: Wilbur's Great Adventure, which was panned by critics.

[23] In 2006, Bynes starred in the teen sports romantic comedy film She's the Man, based on William Shakespeare's Twelfth Night.

Critic Roger Ebert wrote "Of Amanda Bynes let us say that she is sunny and plucky and somehow finds a way to play her impossible role without clearing her throat more than six or eight times.

[33] In August 2007, Bynes teamed up with Steve & Barry's to create her own fashion line called Dear, consisting of apparel and accessories.

"[38] In 2008, she appeared in the Lifetime Television movie Living Proof as the student assistant of Harry Connick, Jr.'s character.

[41][42] In 2009, she was set to star in the comedy Post Grad, but she dropped out and was replaced by Alexis Bledel amid rumors that she was having difficulties.

She starred as Marianne Bryant, the president of a high school Bible study club who becomes the personal nemesis of Stone's character.

[47][50][51] She was going to reunite with former All That cast members at '90s Con in March 2023, her first public appearance since the end of her conservatorship, but she did not attend due to illness.

[63] In May 2013, Bynes was charged with reckless endangerment and marijuana possession after she was found smoking in the lobby of her Manhattan apartment building.

[64] In July 2013, Ventura County, California sheriff's deputies detained her after she allegedly started a small fire in the driveway of a stranger in Thousand Oaks.

[78] On March 20, 2023, Bynes was placed on a 72-hour psychiatric hold after she flagged a bystander for help and called 911 following a psychotic episode in Los Angeles.

[79][81] On June 17, 2023, after she called the police indicating that she had thoughts of self-harm, mental health professionals determined that she needed inpatient treatment.