Ersayın has been working as the Vice President of Design and Innovation in Kale Building Products Group since the beginning of 2011 and is responsible for design and development of products such as sanitary ware, bathroom furniture, fixtures, accessories, ceramics and tiles. His main area of expertise is strategic design management and product development, design process and innovative value management. He is an expert for home appliances, bathroom products, white ware, consumer products and building materials. He has served as a jury member, consultant, publishing board member, speaker and director in many contests, congresses, journals and publications both in Turkey and abroad.

He started his career as an Industrial Product Designer in 1989 in Demirdöküm Engineering and Technology Development Departments, a Building Group Company of Koç Holding, and then he established Design Department and assumed the management of this group. In 2005 he became responsible for Far East Relationships Directorate and bore the management responsibility of DeiChung JV firm, most of shares of which belong to Koç Holding and whose center is in China; he carried out product strategies and product development duties as well as positioning of the group in international and Chinese market.

Ersayın has been a member of Executive Board of Design Turkey since 2005. At the same time, he has also been serving as the President of the Industrial Designers Professional Organization (ETMK) since 2014.