Currently, there have been more than one hundred million confirmed cases of coronavirus disease 2019 (COVID-19), with two million deaths worldwide. This has caused a huge medical burden. Severe COVID-19 patients can experience multi-organ damage, including cardiac injury, kidney injury, and liver injury. About 2.0%–4.9% of COVID-19 cases involve patients with preexisting liver diseases. Additionally, preexisting liver diseases were reported and associated with severity (odds ratio (OR) or risk ratio (RR) = 1.48–1.70) and mortality (OR or RR = 1.08–2.65) among COVID-19 patients. Furthermore, the prevalence of liver injury was 16%–29% in COVID-19 patients. Higher prevalence of liver injury may worsen prognosis in patients (severity: OR or RR = 1.9–2.6; mortality: OR or RR = 1.1–4.0). The mechanisms of this association between liver injury and severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection are complex, including direct cholangiocyte damage induced by SARS-COV-2, cytokine storm, and drug-induced liver injury. In particular, drug-induced liver injury may be the most important reason. This review discusses the epidemiology of COVID-19 and liver dysfunction as well as potential mechanisms underlying the association between COVID-19 and liver dysfunction or other preexisting liver diseases. However, the association between preexisting liver diseases and COVID-19 prognosis and potential mechanisms underlying these associations require further prospective studies.