Kocabaş started her career at Koç Group, had various managerial roles at Arçelik, Marshall Chemicals, Danonesa a joint venture of Group Danone and Sabancı Corporation.

Kocabas joined Turkcell in 2002 as CXO, where she served for 13 years. Human Resources, Construction and Real Estate, Administrative Affairs, IT, Legislative Affairs, Procurement, Strategic Planning were all her work responsibility which enabled Kocabas before leading Corporate Business .She was responsible for profit&loss while working with a wide range of responsibilies such as marketing, sales, product management and services for 5 years. She worked for Turkcell Group until May of 2015. She held chair in the local and international operations of Turkcell like Inteltek Company known as İddaa , Astelit and Best international operations in the region, Global Bilgi Call Center, Turkcell Payment Systems and Turkcell Technology Companies within this period.

Kocabas was the first female President of Peryon Human Management Association which happens to be the oldest civil liberties organization in Turkey. Currently she is involved in the public services department of the same establishment. Kocabas is the first corporate representative of Ethics and Prestige Association, had TKYD and TÜSİAD membership, is in the board of Yönetim Kurulunda Kadın Association and Yeniden Biz Association and at the Consultant Board and mentor of Endeavor .

Currently Kocabas is Board Advisor at Tay Group and Aydın Group; Simit Sarayı and MultinetUP Board Member,Akiş GYO Independent Board Member, Partner at Mentoro Platform and provides companies strategic management consulting services and mentorship .She is working for more than 25 years.

Selen Kocabas is a graduate of İstanbul University School of Economics in English and has a master degree in Human Resources Management and Organizational Behaviour at Marmara University and had Corporate Strategy Programme at Executive Education at Harvard Business School.

Kocabas is a mother to a 20 years old son. She speaks French and English.