Effective use of Big Data can significantly support the development of smart cities and the new digital economy. The aim of the article is a multi-criteria evaluation of IT systems in terms of Big Data processing, taking into account the support for the development of smart cities. The article includes theoretical and empirical research. The adopted criteria for assessing the architecture of IT systems relate to barriers to the implementation of the digital economy in smart cities and the guidelines of international data strategies. The evaluation covered, among other things, cybersecurity and the effectiveness of organizing, storing, and producing new information. The research results allowed us to identify the key factors of Big Data processing efficiency. Based on the research results, an effective model of Big Data processing in organizations was developed. In particular, various data models were analyzed as one of the main elements of software architecture of information systems. The research also focused on data processing techniques such as data warehousing, machine learning, and distributed computing. The efficiency factors of IT systems identified in the research reduce barriers to developing global data strategies and smart cities.