Anna Mazurczak is an attorney, member of the Bar Association in Warsaw. Since 2014, she has been a member of the Human Rights Commission at the Supreme Bar Council and from 2018, the Vice President of the Human Rights Section at the District Bar Council in Warsaw.

In 2012-2018, she worked in the Office of the Ombudsman, where from 2015 she was the Head of the Department of Anti-discrimination Law. Since 2018, she has been a partner in the Knut Mazurczak Adwokaci law firm, the first Polish law firm specializing in matters concerning the legal protection of LGBT persons. She is also a member of the board of the Polish Society of Anti-Discrimination Law. Woman of the Legal Bar 2018 winner.

She represented the Ombudsman in precedent court proceedings concerning the protection of human rights of LGBT people, inter alia, in a case which ended with a decision of the Supreme Administrative Court allowing the transcription (transfer) of a foreign birth certificate in which two mothers were identified as parents and determining the content of the birth certificate of a child born by a transgender man.

She currently specialises in matters relating to the issue of identity documents to children whose foreign birth certificates indicate two persons of the same sex as parents. She also speaks in cases concerning gender determination, including cases concerning the recognition of foreign decisions on gender determination in Poland.