Reiko Tomita was born on September 24th, 1938, in Shinjuku, Tokyo. During World War II her family fled to Saitama, roughly 20 miles north of Tokyo's city center. While her father died during the war, she and her mother eventually returned to Tokyo (Asagaya) following its end.

Tomita attended Tokyo University and was the first woman to enroll in and graduate from the university's department of architecture in 1961. In 1963 she completed her master's course in architecture in Kenzo Tange's atelier (also part of Tokyo University's architecture department).

From 1963-1971 she worked at U Atelier (U-Ken), an architectural office headed by architect Takamasa Yoshizaka. In 1971, she and two other members of U Atelier, Hiroyasu Higuchi and Koichi Otake, left to start their own design practice, Atelier Zo, originally a pun on THO (the first letters of the founding members' last names), "Zo" means "elephant" in Japanese. In the 1980s Atelier Zo evolved into Team Zoo, a cooperative of loosely connected studios, each with its own animal iconography.

Reiko Tomita has taught at Tokyo University, Waseda University, and served as a visiting lecturer at Massachusetts Institute of Technology and Pennsylvania University. Tomita continues to work at Atelier Zo in her 80s.

On her curriculum vitae she notes the following major projects for Atelier Zo on which she worked:

Domo Celakanto (1974)[residential] Domo Arabeska (1974)[residential] Domo Kinyana (1992)[residential] Shinshukan Community Center (1980) [public/institutional] Nago City Hall (1981) [public/institutional] Kasahara Elementary School (1982) [educational] Taiwan Iiran County Hall (1997) [public/institutional] Kutaniyaki Porcelain Museum (2001) [public/institutional] Tsuyama Archives of Western Learning (2009) [public/institutional]