Autism spectrum disorder (ASD) and intellectual disability (ID) are heterogenous and prevalent conditions which may occur in isolation or as a co-morbidity. Psychiatric co-morbidity is common with limited treatment options. Preliminary research into electroconvulsive therapy (ECT) for these conditions has been encouraging. Thus, further research in this patient population is warranted. We conducted a 10-year retrospective review of the electronic medical record and identified intellectually capable individuals with ASD (IC-ASD), and those with ASD+ID or ID who received at least three ECT treatments. 32 patients were identified of which 30 (94%) experienced positive clinical response, defined as a clinical global impression-improvement (CGI-I) score of 3 or less. The average retrospective CGI-I score across all groups was 1.97, and results of a t-test performed on CGI-I scores indicated improvement across all groups [t = - 16.54, df = 31, p < 0.001, 95% CI = (1.72, 2.22)]. No significant adverse events were identified based on clinical documentation. Our findings further support previous ECT research in this patient population.