Müller began her career at Szent Pantaleon Hospital. Then she worked as an occupational physician. From 1991 to 1996 Müller worked as a primary care physician in Nagyvenyim. After that she became Health Commissioner of Dunaújváros. In 2010, as Health Commissioner for the Central Transdanubia region, she was responsible for the cleanup of the Ajka alumina plant accident for which she later received a ministerial award from Sándor Pintér, Interior Minister of Hungary.