Massive advancements have been noticed on the Internet of Things (IoT) integrating smart Homes Energy Management Systems (HEMSs). In the literature, many reviews have been carried out regarding the technological upgrades in the HEMSs. However, a comprehensive review of energy management technologies at the smart cities scale is lacking in the literature. In this paper, a detailed quantitative and Systematic Literature Review (SLR) has been carried out regarding energy management technologies which have been particularly developed for smart cities. With this SLR we have identified research gaps that are restricting the large-scale deployment of robust energy management models in smart cities. Accordingly, this paper presents a discussion about the implementation of state-of-the-art energy management techniques in smart cities. Finally, it is suggested possible next steps for the HEMSs research.