She graduated from Üsküdar American Academy in 2002 and began her studies at the Faculty of Law of Marmara University in the same year. After graduating from the Faculty of Law in 2006, she completed her legal internship at the Istanbul Bar Association. Köstem who has practiced law in Bodrum as a registered lawyer in the Muğla Bar Association  now continues her professional activity as a Member of the Istanbul Bar Association. She got her LLM degree in European Union Law in 2019 upon her graduation from European Union Institute of Marmara University. She is currently continuing her academic studies in Bahçeşehir Üniversity as a Phd student on Private Law.