Tiffani-Amber Thiessen was born on January 23, 1974, in Long Beach, California, USA, to Frank Thiessen, a park designer, and Robyn Ernest, a homemaker. She grew up in Long Beach with her parents and her brothers, professional cyclist Todd (b. 1968) and Schuyler (b. 1977). When Tiffani was 8, her uncle, Roger Ernest, suggested that she try acting and modeling. Soon afterward, she appeared in her first TV commercial, for Peaches and Cream Barbie. From there she started competing in several beauty pageants and, in 1987, she won the Miss Junior America pageant.
That same year, she became popular cheerleader Kelly Kapowski on the teen show Saved by the Bell, a job she kept until 1993. She reprised her role on Saved by the Bell: The College Years until its demise in 1994 after only one season. Over the years, she guest-starred on programs such as Charles in Charge, Married... with Children, Valerie, Step by Step, Blossom, The Powers That Be, Cupid, NewsRadio, Just Shoot Me!, and Two Guys, a Girl and a Pizza Place.
In her new zip code, Thiessen shed her good girl image to play the pot-smoking vixen Valerie Malone, and helped send a jolt of energy into the wilting show as well as into her career. She quickly won over her castmates, including Jennie Garth, who became her best friend. While the show had begun as a more realistic depiction of naïve Midwesterners plunked down in the wealth and opulence of Beverly Hills teen culture, during Thiessen's stint, the storylines around her became more sensational and far-fetched. Perhaps working together was not the best recipe for this particular couple, because Thiessen and Green broke up in 1995. Still, her soaring profile helped her steadily star in a series of TV movies like a deceived wife in "The Stranger Beside Me" (ABC, 1995), a resilient rape victim in "She Fought Alone" (NBC, 1995), a mysterious coma survivor in "Sweet Dreams" (NBC, 1996) and as a small-town woman haunted by ghosts in "Buried Secrets" (NBC, 1996), which she also co-produced.