Refrigeration systems currently utilize 17 of total electric energy, and this consumption is expected to increase by more than 30 by 2050. Moreover, these systems significantly contribute to global warming (10) and environmental degradation. Optimization of these systems can overcome these critical issues, increase thermal efficiency, and decrease the total cost. Refrigeration system optimization problems are complex, multi-modal, non-linear, and time-consuming. Both classic and non-classic (computational intelligence (CI)) methods are successfully applied to overcome these challenges. This comprehensive review presents state-of-the-art theory and application of the most widely used CI techniques such as GA, PSO, SA, DE, HTS, CRO, MOGA, and NSGA II in the optimization of various refrigeration systems. The properties of these algorithms, their computational efficiency, robustness, and applications are highlighted most. Additionally, the authors discuss several surrogate modelling techniques and their applications in refrigeration systems, including ANN, RSM, and regression analysis. According to trend analysis, the major cost function to optimize is the COP, followed by total cost, exergetic efficiency, energy consumption, and cooling capacity. Subsequently, the application of CI approaches has increased dramatically in the optimization of refrigeration systems, where GA and its variants are typically used, and authors are more interested in multi-objective optimization. © 2021 Elsevier Ltd