Background: Pandemics may promote hospital avoidance, and added precautions may exacerbate treatment delays for medical emergencies such as stroke. We sought to evaluate ischemic stroke presentations, management and outcomes during the first year of the COVID-19 pandemic. Methods: We conducted a population-based study, using linked administrative and stroke registry data from Alberta to identify all patients presenting with stroke before the pandemic (Jan. 1, 2016 to Feb. 27, 2020) and in 5 periods over the first pandemic year (Feb. 28, 2020 to Mar. 31, 2021), reflecting changes in case numbers and restrictions. We evaluated changes in hospital admissions, emergency department presentations, thrombolysis, endovascular therapy, workflow times and outcomes. Results: The study included 19 531 patients in the prepandemic period and 4900 patients across the 5 pandemic periods. Presentations for ischemic stroke dropped in the first pandemic wave (weekly adjusted incidence rate ratio [IRR] 0.54, 95% confidence interval [CI] 0.50 to 0.59). Population-level incidence of thrombolysis (adjusted IRR 0.50, 95% CI 0.41 to 0.62) and endovascular therapy (adjusted IRR 0.63, 95% CI 0.47 to 0.84) also decreased during the first wave, but proportions of patients presenting with stroke who received acute therapies did not decline. Rates of patients presenting with stroke did not return to prepandemic levels, even during a lull in COVID-19 cases between the first 2 waves of the pandemic, and fell further in subsequent waves. In-hospital delays in thrombolysis or endovascular therapy occurred in several pandemic periods. The likelihood of in-hospital death increased in Wave 2 (adjusted odds ratio [OR] 1.48, 95% CI 1.25 to 1.74) and Wave 3 (adjusted OR 1.46, 95% CI 1.07 to 2.00). Out-of-hospital deaths, as a proportion of stroke-related deaths, rose during 4 of 5 pandemic periods. Interpretation: The first year of the COVID-19 pandemic saw persistently reduced rates of patients presenting with ischemic stroke, recurrent treatment delays and higher risk of in-hospital death in later waves. These findings support public health messaging that encourages care-seeking for medical emergencies during pandemic periods, and stroke systems should re-evaluate protocols to mitigate inefficiencies.