This paper clarifies the concept of a smart city as a relatively new and current concept in today’ s world and analyses the potential of smart city development based on start-up entrepreneurship in terms of creating new innovative entrepreneurial opportunities. The very concept of a smart city is comlicated and consists of several factors. In this context, a brief overview of the need to develop a smart city initiative and start-up entrepreneurship in Zagreb is given. The data was collected by secondary research (collecting and analyzing sources: works, articles, internet sources, etc.) and primary research. Primary research was conducted in a way of collecting data from all the companies established within the Technology Park Zagreb in 2016 and 2017. The analysis involved a total of 21 companies. This paper focuses on small businesses, applications and projects that together with the government initiatives affect the development of citizens and the city itself. Based on six basic characteristics for determining a smart city, the results of the research were presented and a clearer picture of the role of start-up entrepreneurship as a drive of the economy and development of Zagreb was obtained.