After graduating from the Vienna University of Economics and Business Administration in marketing and finances in 1995, Dejan Turk was employed by McDonald's Slovenija. He began his career as a restaurant manager, later being promoted to the head of human resources and franchises. IN June 1997 he became head of marketing, responsible for marketing activities and corporate communications in Slovenia. In 1998 he was named CEO of McDonald's Slovenija, and a year later the CEO of the whole restaurant chain in Slovenia and Croatia, which includes 30 restaurants with over 1,500 employees. In 2003 he became the CEO of Metropolis Media, which is the largest company for wholesale purchasing of advertising space.

In August 2004 he became the head of marketing and sales at Si.mobil, responsible for marketing, advertising activities, product marketing, customer relations management, as well as all sales activities in Slovenia. In August 2006 Dejan was named as the member of the board, responsible for the market. With his experiences and knowledge he helped bring about a better image of the company and a strong market presence in recent period. In March 2007 he became the Chairman of the management board of Si.mobil.

Under his leadership the company gained certificate for Family Friendly Company and Reputable Employer and a special award in the project Zlata nit (Golden Thread) for one of the best employers in Slovenia. Besides that the company was awarded with Superbrands for most exceptional brands, Advertiser of the Year, Effie for most effective communication campaign, Papirus for best Slovene internal magazine, Prizma for communication excellence, Dejan received IABC Excel award (Excellence in Communication Leadership), 40 most prominent journalists and economic and financial experts awarded him the Director of the year, The Managers' Association of Slovenia chose him to be the Manager of the year etc. Under his leadership the company's customer base grew and reached the number 589.400 customers at the end of 2009. The company also focused a lot of efforts into environmental friendly operations and received the ISO 14001 environmental certificate.