Tomita was born in Okinawa, the daughter of Shiro and Asako Tomita, and she is 1/4 Filipino on her mother's side of the family. Her father was a distinguished Japanese-American man who was interned at Manzanar, California, during part of World War II, then later became a Los Angeles police officer, rising to the rank of sergeant and helping to form the first Asian Task force in that Department.
In 1984, Tomita got her big break by traveling as Queen of Nisei Week to Hawaii when she was selected as part of a casting call by director John G. Avildsen to make her acting debut in The Karate Kid, Part II, playing Ralph Macchio's character's love interest, Kumiko. On the film's set, she met Nobu McCarthy, herself a former beauty queen. McCarthy became a role model, mentor and close friend to Tomita, making it especially difficult when, in 2002, McCarthy died unexpectedly while on location in Brazil with Tomita, filming Gaijin 2 - Ama-me como sou. Tamlyn contributes a lot of her time to non-profit events to help the Japanese-American community in California.
In 1987 Tomita made her Japanese singing debut on the label Polydor. She released a single and an album.
Polydor DX-1515 EP: "Hitomi no Majutsu ~Hypnotized~" c/w "I Can't Stand the Pain"
Polydor H33P-20179 LP: "Sweet Surprise" (Primirive / I Can't Stand the Pain -English Version- / Hitomi no Majutsu ~Hypnotized~ / Arrivederci / Just Say You Love Me / Seiza o Tsunagu Love Song / Beauty and Beast of Love / I Can't Stand the Pain -Japanese Version- / Santa Monica no Koibito e -Instrumental- / Hawaiian Wind / Insult to Injury)