Dorothea Nicolai trained as a dressmaker in Munich, before studying costume at the University of Applied Sciences and Design Hamburg. She spent many years working as a costume assistant, wardrobe mistress, and costume designer in France, Italy, Belgium, and Austria. From 1995 to 1999, she served as head of costume production at the State Opera in Vienna, where she was responsible for the Vienna State Opera Ballet and its large classical ballet productions; at the same time she was costume designer for contemporary choreographies (Christine Gaigg, Nicolas Musin). During this period, she discovered her fascination with movement and costume. From 2000 to 2008, she served as head of costume and make-up at the Salzburg Festival. She was Lecturer in Costume History at the Academy of Fine Arts Munich from 2001 to 2007. She was been head of costumes for Zurich Opera House since 2008.