Background Limited knowledge exists on the association between polypharmacy among older patients diagnosed with cardiometabolic diseases and the risk of clinical outcomes and healthcare utilization. Aim This study aimed to estimate the impact of polypharmacy on clinical outcomes and healthcare utilization in older adults with cardiometabolic diseases. Method A retrospective cohort analysis was performed using data from the Beijing Municipal Medical Insurance Database. The study focused on polypharmacy prescribing patterns in community-dwelling adults 65 years and older with cardiometabolic diseases. Polypharmacy was defined as the use of five or more medications on the index date. The primary outcome included clinical outcomes, including hospitalizations and emergency department visits. The secondary outcome focuses on hospital utilization, specifically medication costs and length of stay. Results The study included a cohort of 405,608 patients. Among these, the most frequently used drug classes in the polypharmacy and non-polypharmacy groups were HMG-CoA reductase inhibitors and dihydropyridines, respectively. After adjustment for covariates, polypharmacy was not associated with an increased risk of hospitalization (odds ratio [OR] 1.09, 95% confidence interval [CI] 0.95-1.26, p = 0.23) or ED visits (OR 1.28, 95% CI 0.97-1.68, p = 0.08). Similarly, no significant association was found with an increase in inpatient medication costs ($2,620.5, 95% CI $2387.3-$2894.3, p = 0.97) or length of stay (3.98 days, 95% CI 3.68-4.30 days, p = 0.79). However, polypharmacy was associated with higher medication costs in outpatient settings ($73.07, 95% CI $72-$74, p < 0.05) and ED visits ($51.2, 95% CI $44.5-$59.1, p < 0.05). Conclusion Although polypharmacy is associated with increased healthcare costs in outpatient settings and ED visits, it does not significantly increase the risk of hospitalization or ED visits when properly managed.