Digital city security is one of the most important elements that should accompany technological implementation in local government. The purpose of the article is to present the key areas of smart city development and the need to implement high-quality cyber security that slowly for sustainable growth of urban spaces. The paper uses research areas including monographic, observational and individual case method. The author emphasizes that only the symbiosis of technological growth and cyber security can permanently change the urban fabric. Lack of adequate forms of digital security for the ever-newer technological investments, can hinder the development of cities and discourage people from investing in smart cities. Cyber security in a smart city is therefore a key point connecting public expectations with rapid development.