Background: Only a few studies have investigated the affect of rheumatoid arthritis (RA) on the risk of cerebrovascular disease (CVD)/coronary artery disease (CAD) in young adults. This study, therefore, examined the association between RA and the risk of CVD/CAD in young adults and the interaction effects between cardiovascular risk factors and RA on the risk of CVD/CAD. Methods: Data regarding 52,840 subjects (10,568 patients with RA and 42,272 age-, sex-, urbanization-, and income-matched non-RA controls) were collected from the National Health Insurance Research Database (NHIRD) in 2006. All subjects were followed until a CVD or CAD diagnosis, or death, or December 31, 2011. The hazard ratios (HRs) of CVD/CAD were estimated using Cox proportional hazard models. The interaction effects between cardiovascular risk factors and RA on the risk of CVD/CAD were assessed using additive and multiplicative models. Results: RA increased the risk of CVD/CAD in young adults, especially those at risk of ischemic stroke (adjusted HR, 3.48; 95% confidence interval (CI), 2.16–5.61). Even without comorbidity at baseline, patients with RA still had a 2.35-fold greater risk of CVD/CAD relative to those without RA. RA and hypertension interacted positively on the risk of CVD/CAD. The highest CVD/CAD risk was found in patients with RA and hypertension (HR, 9.08; 95% CI, 7.22–11.41) relative to subjects without RA and hypertension. Conclusion: RA is an independent risk factor for CVD/CAD in young adults. The government should develop policies for preventing early onset hypertension to reduce the incidence of CVD/CAD among young patients with RA.