This study aimed to comprehensively evaluate whether income affects long-term health outcomes for older patients who underwent percutaneous coronary intervention (PCI) provided by a universal health coverage system. Data were from the Latter Stage Elderly Healthcare Insurance database in Fukuoka Prefecture, Japan. A total of 5625 individuals aged ≥65 years who underwent PCI in 2014-2016 were included. Cox proportional hazards models were used to assess the association between income status and the incidence of health outcomes. With a median follow-up of 1095 days, 554 acute myocardial infarction (AMI) cases, 1075 stroke cases, 1690 repeat revascularization cases, and 1094 deaths were observed. Risk of all-cause mortality decreased significantly with increasing income level in both unadjusted and adjusted Cox regression models. Patients in the low-income level had a significantly higher rate of AMI (log-rank P = 0.003), stroke (log-rank P = 0.039), and all-cause mortality (log-rank P = 0.001) compared with patients in the high-income level. Observed rates for repeat revascularization also were high in the first year after PCI. In the Japanese universal health setting, low-income patients had a comparatively higher mortality risk after PCI. Poor long-term outcomes might be attributed to patients' baseline characteristics rather than treatment processes.