Introduction: Impaired kidney function is a robust risk factor for cardiovascular mortality. Age-related annual kidney function decline of 1.0 ml/min per 1.73 m2 after age 40 years is doubled in post−myocardial infarction (MI) patients. Methods: We investigated the impact of the number of cardiovascular risk factors (including unhealthy lifestyle) on annual kidney function decline, in 2426 post-MI patients (60−80 years) of the prospective Alpha Omega Cohort study. Glomerular filtration rate was estimated by serum cystatin C (eGFRcysC) and combined creatinine−cystatin C (eGFRcr-cysC), using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations from 2012. Data were analyzed by multivariable linear and logistic regression. Results: At baseline, mean (SD) eGFRcysC and eGFRcr-cysC were 81.5 (19.6) and 78.5 (18.7) ml/min per 1.73 m2, respectively. Of all patients, 79% were men, 19% had diabetes, 56% had high blood pressure (≥140/90 mm Hg), 16% were current smokers, 56% had high serum low-density lipoprotein (LDL of ≥2.5 mmol/l), and 23% were obese (body mass index of ≥30.0 kg/m2). After multivariable adjustment, the additional annual eGFRcysC decline (95% confidence interval) was as follows: in patients with versus without diabetes, −0.90 (−1.23 to −0.57) ml/min per 1.73 m2; in patients with high versus normal blood pressure, −0.50 (−0.76 to −0.24) ml/min per 1.73 m2; in obese versus nonobese patients, −0.31 (−0.61 to 0.01) ml/min per 1.73 m2; and in current smokers versus nonsmokers, −0.19 (−0.54 to 0.16) ml/min per 1.73 m2. High LDL was not associated with accelerated eGFRcysC decline. Similar results were obtained with eGFRcr-cysC. Conclusion: In older, stable post-MI patients without cardiovascular risk factors, the annual kidney function decline was −0.90 (−1.16 to −0.65) ml/min per 1.73 m2. In contrast, in post-MI patients with ≥3 cardiovascular risk factors, the annual kidney function decline was 2.5-fold faster, at −2.37 (−2.85 to −1.89) ml/min per 1.73 m2.