Objectives This study aimed to investigate the mediating effects of anxiety and sleep quality in the relationship between anxiety sensitivity and irritability among psychiatric patients. Methods A total of 105 psychiatric patients completed questionnaires on anxiety sensitivity (Korean version of the Anxiety Sensitivity Index-3), irritability (Korean version of the Brief Irritability Test), anxiety (Korean-Beck Anxiety Inventory), and sleep quality (Korean version of Pittsburgh Sleep Quality Index). Data analyses were conducted using regression analyses and the bootstrap sampling method. Results The major findings of this study were as follows: First, anxiety sensitivity positively pre-dicted irritability. Second, anxiety significantly mediated the relationship between anxiety sensitiv-ity and irritability, but not sleep quality. Last, the sequential mediating effect of anxiety and sleep quality was significant in the relationship between anxiety sensitivity and irritability. Conclusion These results suggest that anxiety and sleep quality should be considered in the pathway from anxiety sensitivity to irritability. Therefore, addressing anxiety and sleep quality in anxiety sensitivity interventions may help prevent the development of irritability.