Baier earned a diploma in mathematics at the University of Mannheim in 1990, and stayed at the same university for graduate study in computer science, completing her Ph.D. there in 1994.[2] Her dissertation, Transitionssystem- und Baum-Semantiken für CCS, was supervised by Mila Majster-Cederbaum.[4] She earned a habilitation at Mannheim in 1999.[2]
She became an associate professor for computer science at the University of Bonn in 1999, and moved to TU Dresden as a professor in 2006.[2]