Bynes was born in Thousand Oaks, California, the youngest of three children of Lynn Bynes (née Organ), a dental assistant and office manager, and Rick Bynes, a dentist. Her father is Catholic, and is of Irish, Lithuanian, and Polish descent. Her mother is Jewish (from a family from Romania, Russia, and Poland). Bynes' maternal grandparents are Canadians from Toronto, Ontario.
Bynes attended a comedy camp, and began professionally acting at the age of 7, appearing in a television advertisement for Buncha Crunch candies. During her childhood, she also appeared on stage in versions of Annie, The Secret Garden, The Music Man, and The Sound of Music. Bynes rose to prominence with her various roles in All That for seasons three through six. She later became a regular member of Nickelodeon's Figure It Out (1997–1999). At the age of 13, she began starring in her own sketch comedy show, The Amanda Show (1999–2002). In 2002, Amanda began to establish her fan base with her debut film role in Big Fat Liar (2002) opposite Frankie Muniz, and a co-starring role in the WB sitcom What I Like About You (2002–06) with Jennie Garth, which gained positive reviews. She also made her voice-over debut in Charlotte's Web 2: Wilbur's Great Adventure and later in the animated comedy Robots (2005).
Amanda's film career took off over the next two years, with a role in the romantic comedy Lovewrecked (2005) and a starring role in the comedy She's The Man (2006). She also appeared on the cover of Vanity Fair's July 2003 edition. Bynes was named one of Teen People's "25 Hottest Stars Under 25" in 2006. Later that year, she starred in She's the Man, a comedy based on William Shakespeare's Twelfth Night. Bynes appeared in another romantic comedy, Love Wrecked. In 2006 release the film She's the Man but released after it, showing in cinemas outside of the United States in 2005 and 2006 and debuting in the U.S. on the ABC Family network on January 21, 2007.
Bynes' next role was Penny Pingleton in Hairspray. The film was a critical and commercial success. Hairspray went on to become Amanda's most successful film at the time. Bynes was featured on the Hairspray soundtrack, which went on to get a Grammy nomination. Bynes' next role was in another comedy, Sydney White, released on September 21, 2007. In August 2007, Bynes teamed up with Steve & Barry's to create her own fashion line called Dear, consisting of apparel and accessories. The line was cut short when Steve & Barry's filed Chapter 11 bankruptcy in 2008 and went out of business in January 2009. In 2008, Bynes appeared in the Lifetime Television movie Living Proof as the student assistant of Harry Connick, Jr.'s character. Bynes was also originally set to star in the 2009 comedy Post Grad, but she was replaced by Alexis Bledel.
In June 2009, Bynes signed a two-picture deal with Screen Gems. The first of the two movies was the 2010 teen comedy Easy A, starring Emma Stone and Lisa Kudrow. The film was once again another critical and commercial success with many critics praising Bynes' role. The film after Easy A would have been a starring role. Bynes also planned to reprise her role as Penny Pingleton in the sequel to Hairspray. However, Hairspray 2 was canceled. Bynes was also originally set to star in the comedy Hall Pass but dropped out and was replaced by Alexandra Daddario. Appearing on the cover of the February 2010 issue of Maxim magazine, highlighting her photo spread inside, Bynes stated: "I think every shot I did was sexy." In July, Bynes stated that she planned to retire from acting, but decided to have an indefinite hiatus. During this time she studied fashion design at the Fashion Institute of Design & Merchandising in Irvine.
During an interview in June 2017, Bynes announced that she wanted to return to acting, but only in television.
In 2007, Bynes described herself as Jewish, and also stated: "As far as religion, I was raised both. I learned about both Judaism and Catholicism. My parents said it was up to me to decide (which faith to adhere to) when I grew up. I'm sort of a spiritual person anyway. I haven't decided yet on a religion. I don't know yet exactly what I believe."
Bynes is interested in illustration and fashion design. She has previously had her own fashion line sold nationwide, and moved from Los Angeles to New York in order to facilitate her fashion career. In 2008, Bynes briefly dated Seth MacFarlane after voicing a character in an episode of MacFarlane's show Family Guy. In December 2013, Bynes enrolled at the Fashion Institute of Design & Merchandising in Irvine for 2014.
In 2012, Bynes was charged with driving under the influence (DUI) in West Hollywood. Two years later, the charge was dropped and she received a three-year probation.
In 2013, Ventura County sheriff's deputies detained her after she allegedly started a small fire in the driveway of a stranger. She was hospitalized under a 72-hour mental-health evaluation hold. Bynes' parents filed for conservatorship of their daughter shortly after her hospitalization began. In August, Bynes' mother was granted a temporary conservatorship over Bynes' affairs." In October 2014, Bynes' mother again received conservatorship.Albums appearances