Sixty patients with severe COVID-19 were randomized to receive routine care plus intravenous Xuebijing injection (n=30) or routine care alone (n=30) for the suppression of inflammatory response and management of symptoms. The primary outcome of interest was peripheral blood lymphocyte and interleukin (IL)-6 levels which were measured at 1, 7 and 14 days follow-up. Secondary outcomes of interest included 28 day mortality, the rate of mechanical ventilation, septic shock, severity progression (to critically ill; moderate illness), leucocyte levels, C-reactive protein (CRP) levels, IL-8 levels, tumor necrosis factor (TNF)-alpha levels, length of intensive care unit (ICU) stay, time to improvement of clinical symptoms, and the incidence of adverse events. Outcomes were assessed up to 14 days follow-up for biochemical outcomes and until the end of the trial for remaining outcomes. Results revealed statistically significantly lower IL-6 levels in the Xuebijing group compared to the control group at 7 and 14 days follow up (p<0.05 for both). However, no statistical significant differences were observed between the two groups in leucocyte levels at any time point (p>0.05 for all). Moreover, IL-8 and TNF-alpha levels were statistically significantly lower in the Xuebijing group at 7 and 14 days follow-up (p<0.05 for all), whilst CRP levels and lymphocyte levels were statistically significantly in favour of the Xuebijing at 14 days follow-up only (p<0.05 for both). The incidence of acute respiratory distress syndrome, mechanical ventilation, invasive mechanical ventilation, non-invasive mechanical ventilation, and septic shock were all statistically significantly lower in the Xuebijing group (p<0.05 for all). Furthermore, the incidence of 28-day mortality was not statistically significantly different between groups; however, the rate of mortality was lower in the Xuebijing group (3.45% vs. 25%, p=0.557). The number of cases that developed into critically ill cases was statistically significantly lower in the Xuebijing group (p=0.032), and more patients in the Xuebijing group developed into moderate cases (p=0.048). The time to improvement of fever, cough, shortness of breath, and fatigue was statistically significantly quicker in the Xuebijing group compared to the control group (p<0.05 for all), and the length of ICU stay was statistically significantly shorter in the Xuebijing group (p=0.004). Lastly, the incidence of abnormal liver function, renal dysfunction, and rash were not statistically different between the two groups (p>0.05 for all). No cases of anaphylactic shock were observed in either group.