Background and Objectives: We investigated epidemiological factors and outcomes, including the development of complications, for patients with appendicitis according to three sequential coronavirus disease 2019 (COVID-19) pandemic periods, divided by specific time points.Materials and Methods: This observational study included patients with acute appendicitis who arrived at a single-center between March 2019 and April 2022. The study divided the pandemic into three periods: period A as the first phase of the pandemic (from 1 March 2020 to 22 August 2021), period B as the time period the medical system stabilized (from 23 August 2021 to 31 December 2021), and period C as the time period of the exploration of patients with COVID-19 in South Korea (from 1 January 2022 to 30 April 2022). Data collection was based on medical records. The primary outcome was presence or absence of complications and the secondary outcomes were the time taken from ED visit to surgical intervention, the presence and time of the first administration of antibiotics, and the hospital stay time.Results: Of 1,101 patients, 1,039 were included, with 326 and 711 patients before and during the pandemic, respectively. Incidence of complications was not affected during the pandemic (before the pandemic 58.0%; period A 62.7%; period B,55.4%; and period C 58.1%;p= 0.358). Time from symptom onset to emergency department (ED) arrival significantly decreased during the pandemic (before the pandemic 47.8 ± 84.3 h; pandemic 35.0 ± 54 h;p= 0.003). Time from ED visit to the operating room was statistically significantly increased during the pandemic (before the pandemic 14.3 ± 21.67 h; period A 18.8 ± 14.02 h; period B 18.8 ± 8.57 h; period C 18.3 ± 12.95 h;p= 0.001). Age and time from symptom onset to ED arrival were variables affecting the incidence of complications; however, they were not affected during the pandemic (age, OR 2.382; 95% CI 1.545–3.670; time from symptom onset to ED arrival, OR 1.010, 95% CI 1.006–1.010;p< 0.001).Conclusions: This study found no differences in postoperative complications or treatment durations between pandemic periods. The incidence of appendicitis complications was significantly influenced by age and the duration between the onset of symptoms and arrival at the emergency department, but not by the pandemic period itself.