The novel coronavirus 2019 (COVID-19) pandemic is rapidly advancing across the globe despite drastic public and personal health measures. Antivirals and nutritional supplements have been proposed as potentially useful against SARS-CoV-2 (virus that causes COVID-19), but few have been clinically established. Lactoferrin (Lf) is a naturally occurring and non-toxic glycoprotein that is orally available as a nutritional supplement and has established in vitro anti-viral efficacy against a wide range of virus including SARS-CoV, a closely related corona virus to SARS-CoV-2 (virus that causes COVID-19). Furthermore, Lf possesses unique immunomodulatory and anti-inflammatory effects that may be especially relevant to the pathophysiology of severe COVID-19 cases. We review the underlying biological mechanisms of Lf as antiviral and immune regulator, and propose its unique potential as a preventative and adjunct treatment for COVID-19. We hope that further research and development of Lf nutritional supplementation would establish its role for COVID-19.