Katerina Sakellaropoulou was born in 1956 in Thessaloniki, Greece.

She has graduated from the Arsakeio-Psychiko School and earned a degree from the National and Kapodistrian University of Athens Law School.

In 1982, after succeeding in a competition, she was appointed Assistant Judge at the Council of State, the Supreme Administrative Court of Greece. In 1988, she was promoted to the rank of Associate Councillor, in 2000 to the rank of Councillor of State, in 2015 she was appointed Vice-President and in 2018 President of the Council of State. She served as Associate Councillor and Vice-President at the 3rd Chamber and as a Councillor at the 5th Chamber.

She has served, inter alia, as President of the Association of Judges of the Council of State, as President of the Hellenic Society for Environmental Law and she has been a member of the Society of Greek Judges for Democracy and Freedoms and of the Hellenic Scientific Society for Urban Planning and Development Law. She has taught for long environmental law at the National School of Judges.

On 22 January 2020 she was elected by the Hellenic Parliament as the first female President of the Hellenic Republic and assumed office on 13 March.

In June 2021 she was awarded an honorary doctorate by the Law School of the Aristotle University of Thessaloniki.

She has authored several articles on matters of environmental and urban development law, gender equality, protection of individual rights and respect for the rule of law.

She has a daughter named Niovi and lives with her partner Pavlos Kotsonis.