Šimić was born in Zagreb, PR Croatia, Yugoslavia on 9 June 1963, but moved with her mother and sister to Rotterdam in 1979 at the age of 16.

In 1992, she recorded a version of "Can't Take My Eyes Off You" with Dutch singer Gerard Joling.

Her first album was released in 1993 and included the hit "Feel Good" which reached #25 in the Netherlands Top 40.

A full album produced by Stock & Aitken's in-house producers Dave Ford, Julian Gingell and Peter Day called New Look was released in Japan (titled Santa Maria) and the Netherlands.

In 2008, Tatjana made a comeback to the music scene with the Dutch language song Ik Laat Je Gaan, a cover of Croatian artist Tony Cetinski's Blago Onom Tko Te Ima, which left her signature disco sound behind for a more rock pop style.