Catatonia is a severe clinical syndrome which has been increasingly reported in autism spectrum disorder (ASD). The prevalence of catatonia in ASD is unknown. Diagnosing catatonia in ASD is complicated by overlapping clinical features such as mutism, stereotypies, and echophenomena. Here, we present the clinical histories of two individuals with ASD and catatonia who were successfully treated with clozapine. We have reported on a novel potential treatment option for catatonia in ASD. Additional studies are needed to evaluate the safety, efficacy, and tolerability of clozapine for the treatment of catatonia in ASD.