Advanced oxidation processes (AOPs) such as cavitation and ozonation have been used as an alternativeand effective option for the treatment of wastewater with difficult to biodegrade compounds. In thisreview, the necessity and advantages of combining hydrodynamic cavitation with ozonation (HC/O3)were initially discussed. The discussion of the mechanism of the HC/O3 process revealed the presenceof both mechanical and chemical effects. Overviews of earlier work with HC/O3 technology were thensummarised to show the positive synergies and the HC devices in different wastewater treatments. Recommendations were given for parameter selection by analysing the impact of important operatingparameters on process performance. Energy efficiency and cost comparisons indicated that the HC/O3process was more cost effective than the individual process. Overall, the HC/O3 process with optimisedconditions is able to increase the degradation rate of refractory pollutants by more than 40% comparedto the HC process alone.