The impact of myosteatosis on the outcomes of digestive malignancies has gained great attention recently. However, studies on the impact of myosteatosis show inconsistent results. We conducted a meta-analysis to clarify the relationship between myosteatosis and the overall survival of digestive cancer patients. The systematic literature search was conducted on PubMed/MEDLINE, Web of Science, and Embase from inception through March 27, 2021. Meta-analysis was performed using the random-effects model. Out of 3451 studies screened, 47 studies including 21,194 patients passed the screening criteria. The average prevalence of myosteatosis was 46.4%. Patients with myosteatosis had 44% increased mortality risk compared with non–myosteatosis patients (HR: 1.44, 95% CI: 1.33-1.55, P < .05). The predictive value of myosteatosis held regardless of country zone, study design, statistical model, Newcastle-Ottawa Scale (NOS) scores, treatment, sample size, and tumor stage. Nevertheless, the predictive value of myosteatosis was only evident for patients with esophagogastric cancers, cholangiocarcinoma/pancreatic cancers, or colorectal cancers. Overall, the results of this meta-analysis were robust based on sensitivity, subgroup, meta-regression, and trial sequential analyses and suggested that myosteatosis predicted worse overall survival (OS) in digestive malignancies patients.