With her final exam at the Dutch Film and Television Academy, Zinderend, she won a Cannon Award in 1988.

In 1996 Van der Oest made her first long movie,[clarification needed] De nieuwe moeder (The New Mother).

With Zus & Zo, loosely based on Chekhov's The Three Sisters, Van der Oest directed her first mainstream film in 2001.

The realistic characters and the relations among the individuals from her former movies remained central, but there was more humour added, and an English script doctor made some changes, resulting in an Oscar nomination.

Hereafter she created the English thriller/fairytale Moonlight (2002) about the relation between a 13-year-old girl and a balloon swallower of the same age; the film Madame Jeannette, situated in the Suriname-community (which was a great success in the Amsterdam Bijlmer area in 2004); and the film Verborgen gebreken (2004), based on a book by Renate Dorrestein.