Backgroud The association between underlying comorbidities and cardiac injury and the prognosis in coronavirus disease 2019 (COVID-19) patients was assessed in this study. Hypothesis The underlying comorbidities and cardiac injury may be associated with the prognosis in COVID-19 patients. Methods A systematic search was conducted in PubMed, EMBASE, Web of science, and The Cochrane library from December 2019 to July 2020. The odds ratio (OR) and 95% confidence intervals (95% CI) were used to estimate the probability of comorbidities and cardiac injury in COVID-19 patients with or without severe type, or in survivors vs nonsurvivors of COVID-19 patients. Results A total of 124 studies were included in this analysis. A higher risk for severity was observed in COVID-19 patients with comorbidities. The pooled result in patients with hypertension (OR 2.57, 95% CI: 2.12-3.11), diabetes (OR 2.54, 95% CI: 1.89-3.41), cardiovascular diseases (OR 3.86, 95% CI: 2.70-5.52), chronic obstractive pulmonary disease (OR 2.71, 95% CI: 1.98-3.70), chronic kidney disease (OR 2.20, 95% CI: 1.27-3.80), and cancer (OR 2.42, 95% CI: 1.81-3.22) respectively. All the comorbidities presented a higher risk of mortality. Moreover, the prevalence of acute cardiac injury is higher in severe group than in nonsevere group, and acute cardiac injury is associated with an increased risk for in-hospital mortality. Conclusion Comorbidities and acute cardiac injury are closely associated with poor prognosis in COVID-19 patients. It is necessary to continuously monitor related clinical indicators of organs injury and concern comorbidities in COVID-19 patients.