Innovations emerging in the dynamic environment of technological developments lead to new situations in social and economic fields. Cities are one of the important areas where these developments are reflected. Thus, smart cities and big data concepts come up and these developments cause changes in services provided in cities. However, these developments bring along some negativities, as well. The main purpose of this study is to examine the approaches and principles that have come to fore in order to ensure the privacy and security of big data in smart cities. Basically, the answer to this question is sought: what principles, approaches and practices come to the forefront in order to ensure the confidentiality and security of big data that is an important part of smart cities? The answer is sought through the relevant literature, legal regulations and international decisions. According to the general results of the study, it is understood that there are not any consensual standards on data security at global level. However, some regulations draw attention. At this point, the “General Data Protection Regulation (GDPR)” which came into force in 2018 is important. However, some principles and approaches are gaining importance. At the end of the study, some suggestions about policies are made according to the results obtained