Privacy and Security in big data and smart cities play a major role to ensure better quality of citizens life. Privacy emphasizes on the data being collected, shared, and used in the right manner, and security focuses on protecting the data from intruders’ attack, and exploitation of data for other purposes such as criminal behavior. This paper aims to discuss the issue of privacy and security of mobile users in big data and smart cities. First, based on big data privacy and security challenges, classification, and models, we identify the privacy and security requirements for a mobile user. Then, we propose a generic architecture and an algorithm for the management of privacy and security of a mobile user in a smart environment. This architecture groups the main components required for implementing the proposed algorithm that ensure the privacy and security of mobile users in smart cities.