Aim The inconsistent effects of lopinavir-ritonavir (LPV/r) on COVID-19 seem to be caused by the therapeutic window. In the present study, we aim to present the effects of early LPV/r treatment on patients with severe COVID-19. Methods The demographics, characteristics, treatments, SARS-CoV-2 test results and outcomes of 19 patients with severe COVID-19 treated with LPV/r within 12 days of onset of symptoms were retrospectively assessed. Results Within 3 days of admission, three (15.79%) patients received noninvasive ventilation, and 16 (84.21%) patients received highflow oxygen support. The median duration between the onset of symptoms and initiating LPV/r therapy was 9 (range 2-12) days. The median course of LPV/r treatment was 11 (range 7-17) days. One of the 19 patients (5.26%) died. Of the 18 patients discharged, the median hospital stay was 17 (range 11-45)days. At day 6 after LPV/r therapy was initiated, 68.42% of patients were virologically cured, increasing to 84.22% at day 12. Conclusion In this cohort of patients with severe COVID-19 who were treated with LPV/r within 12 days of the onset of symptoms, clinical improvement was observed in 18/19 patients (94.74%). Randomised controlled trials are urgently needed to further evaluate this strategy.