Naoko Mori was born in Nagoya, Japan in 1975. When she was four years old she moved with her family to New Jersey, and eight years later to Surrey, England. Naoko took singing lessons and attended stage school and, at the age of seventeen, appeared in London's West End in the leading role of 'Miss Saigon', opposite John Barrowman, with whom she later appeared in the television sci-fi series 'Torchwood'. In the 1990s she appeared regularly on British TV as a hospital receptionist in 'Casualty' and as a friend of Julia Sawalha, Jennifer Saunders' studious daughter, in the comedy ' Absolutely Fabulous.' This was alternated with film work such as 'Topsy-Turvy', playing a Japanese girl who helped inspire Gilbert and Sullivan to pen 'The Mikado.' A small role in the 2005 revival of cult TV horror/sci-fi series 'Dr. Who', playing computer expert Tosh Sato, led to her being cast in one of the regular leads in its 2006 earthbound spin-off 'Torchwood'.

Along with Freema Agyeman, John Barrowman, Eve Myles and Gareth David-Lloyd, she is one of only five actors to play the same character (Toshiko Sato) in both "Doctor Who" (2005) and "Torchwood" (2006).