In vitro circular RNA (circRNA) preparation methods have been gaining a lot of attention recently as several reports suggest that circRNAs are more stable with better performances in cells and in vivo than linear RNAs in various biomedical applications. Self-splicing ribozymes are considered a major in vitro circRNA generation method for biomedical applications due to their simplicity and efficiency in circularization of gene of interest. This review summarizes updates and discusses recently developed self-circularization methods based on the self-splicing ribozyme such as group I and II intron ribozymes and pros and cons of each method to prepare circRNA in vitro.