OBJECTIVE: Electroconvulsive therapy (ECT) is an important but underused treatment for severe psychiatric illnesses. We sought to examine the variability of ECT utilization at a population level and between several subgroups. We also sought to quantify the impact of the COVID-19 pandemic on ECT utilization. METHODS: We used population level data from Ontario to examine all ECT procedures administered from 1 January 2007 to 31 December 2023. Our primary measure of variability was the rate of ECT procedures per 1,000 population. We included three subgroups at time of ECT procedure: age (18-39, 40-64, and 65+), biologic sex (male/female), and Ontario Health (OH) region of residence (West, Central, Toronto, East, North West, North East). To quantify the impact of the COVID-19 pandemic we calculated the change in ECT rate from 2019 to 2020 (acute effect) and 2019 to 2023 (persistent effect). RESULTS: There were 450,381 ECT procedures delivered during the observation period. The yearly rate of ECT increased from 1.69 per 1,000 in 2007 to a peak of 3.08 per 1,000 in 2019. In 2023 the greatest per capita rates of ECT use were in the 65+ age group, female sex, and North East geographic region. In 2023, the rates of ECT use in different geographic regions ranged from 1.28 (North West) to 4.19 per 1,000 (North East). The COVID-19 pandemic resulted in an immediate 26.73%, followed by a 17.47% persistent drop in the rate of ECT with notable regional heterogeneity. CONCLUSIONS: While ECT use increased over time, there were differences in this increase between age groups, biological sex, and geographic regions. The COVID-19 pandemic had significant immediate and persistent impacts on the rates of ECT use highlighting the need for ongoing population level monitoring of this important treatment.