Urban spaces play a crucial role in shaping the happiness of individuals and communities. However, understanding the factors that contribute to urban happiness is challenging due to the complex and subjective nature of the concept, as well as the scattered nature of the relevant literature. This paper presents a systematic review aimed at identifying the factors that contribute to the happiness of citizens in urban public spaces. The review, which followed the PRISMA method, includes literature from eight academic search engines covering the period from 2000 to 2023. A total of 57 papers were analyzed, resulting in the identification of 64 factors across eight domains: physical, ecological, visual, functional, social, subjective, political, and personal aspects. This comprehensive overview of these factors provides a broad landscape of influences on urban happiness. Policymakers and urban planners can use this overview to enhance citizens’ quality of life and happiness.