Background To determine on a national basis the surgical activity regarding appendectomies during the first Italian wave of the COVID-19 pandemic. Major surgical societies advised using non-operative management of appendicitis and suggested against laparoscopy during the COVID-19 pandemic. Methods Multicenter, observational study investigating the outcomes of patients undergoing appendectomy in the two months of March-April 2019 vs. March-April 2020. The primary outcome was the number of appendectomies performed during each of the two months, classified according to the American Association for the Surgery of Trauma (AAST) score. Secondary outcomes were the type of surgical technique employed (laparoscopic vs. open), and the complication rates. Results 1541 patients with acute appendicitis underwent surgery during the two study periods. 1337 (86.8%) patients met the study inclusion criteria. 546 (40.8%) patients underwent surgery for acute appendicitis in 2020 and 791 (59.8%) in 2019. Patients with complicated appendicitis operated in 2019 were 76 (9.6%) vs. 87 (15.9%) in 2020 (p = 0.001). An increase in the number of post-operative complications was found in 2020 (15.9%) compared to 2019 (9.6%) (p < 0.001). The following determinants increased the likelihood of complication occurrence: undergoing surgery during 2020 (+ 67%), having a unit AAST (+ 26%) increase, having waited for surgery > 24 h (+ 58%), being the surgeon aged > 40 years (+ 47%), undergoing open surgery (+ 112%) and being converted to open surgery (+ 166%). Conclusions In Italian hospitals, in March and April 2020, the number of appendectomies has drastically dropped. Patients undergoing surgery during the first pandemic wave were more frequently affected by more severe appendicitis than the previous year's timeframe and a higher complication rate was reported. Trial registration: ResearchRegistry ID 5789.