Background: The C-reactive protein–triglyceride–glucose index (CTI) integrates inflammation and insulin resistance, but its association with adverse outcomes in acute myocardial infarction (AMI) patients remains unclear. This study aimed to investigate the association between CTI and adverse outcomes, including major adverse cardiac events (MACEs), all-cause death, cardiac death, and myocardial infarction in AMI patients. Methods: The CTI of patients with acute myocardial infarction was calculated and divided into three groups according to its tertiles. Multivariable Cox regression, restricted cubic spline analysis, survival analysis, and correlation heat map analysis were used to explore the association between the CTI and adverse outcomes such as major adverse cardiac events (MACEs), cardiac death, all-cause death and myocardial infarction in patients with acute myocardial infarction. Results: A total of 965 patients were enrolled in this study. In the adjusted Model 3, CTI remained significantly associated with myocardial infarction (Q3 vs. Q1: HR = 2.40, 95% CI: 1.37–4.17, p = 0.001; p for trend = 0.001). However, the associations with MACEs (HR = 1.29, p = 0.161), all-cause death (HR = 1.28, p = 0.337), and cardiac death (HR = 1.78, p = 0.221) were not statistically significant after full adjustment. Restricted cubic spline analysis identified a threshold effect for myocardial infarction at CTI > 5.92, above which the risk increased 5.61-fold (HR = 5.61, 95% CI: 2.94–10.71, p < 0.001). The Kaplan–Meier survival curve showed that the higher the CTI tertiles, the higher the incidence of adverse outcomes. Conclusions: Elevated CTI levels were independently associated with an increased risk of myocardial infarction in AMI patients.