Background: Fragmented QRS (fQRS) is an ECG pattern that reflects inhomogeneity of ventricular conduction, represents myocardial scar, and is a poor prognostic marker in several cardiac conditions. This study aimed to evaluate the prognostic impact of fQRS on in-hospital mortality and adverse outcomes in myocardial infarction (MI) patients. Methods: We conducted a systematic search using 4 databases, including PubMed, Embase, Web of Science, and Cochrane CENTRAL from inception to July 20, 2024, without language restrictions. The inclusion criteria were studies that included MI patients and compared the in-hospital mortality rate and adverse events between fQRS and non-fQRS groups. Results: After a systematic review, 20 studies involving 6,785 participants were included in this meta-analysis. We used a random-effects model for the meta-analysis. The presence of fQRS was associated with an increased risk of in-hospital mortality compared to non-fQRS, with an odds ratio (OR) of 4.21 (95%CI 2.90 to 6.12), p<0.01. Sensitivity analysis, including studies exclusively enrolled STEMI patients or used percutaneous coronary intervention as the method of revascularization, reported consistent findings. Moreover, the presence of fQRS significantly increased the risk of cardiovascular death, major adverse cardiac event, heart failure, and cardiogenic shock in MI patients during hospitalization. However, the stroke rate was not significantly different. Conclusions: The presence of fQRS is associated with a higher risk of in-hospital mortality and adverse cardiac outcomes in MI patients. fQRS is a potential non-invasive tool for early risk assessment in MI patients.