Background: National investigations on age-specific modifiable risk factor profiles for cardiovascular disease (CVD) and mortality are scarce in China, the country that is experiencing a huge cardiometabolic burden exacerbated by population ageing. Methods: This is a nationwide prospective cohort study of 193,846 adults in the China Cardiometabolic Disease and Cancer Cohort Study, 2011-2016. Among 139,925 participants free from CVD at baseline, we examined hazard ratios and population-attributable risk percentages (PAR%s) for CVD and all-cause mortality attributable to 12 modifiable socioeconomic, psychosocial, lifestyle, and metabolic risk factors by four age groups (40-<55 years, 55-<65 years, 65-<75 years, and >= 75 years). Findings: Metabolic risk factors accounted for 52.4%, 47.2%, and 37.8% of the PAR% for CVD events in participants aged 40-<55 years, 55-<65 years, and 65-<75 years, respectively, with hypertension being the largest risk factor. While in participants aged >= 75 years, lifestyle risk factors contributed to 34.0% of the PAR% for CVD, with inappropriate sleep duration being the predominant risk factor. Most deaths were attributed to metabolic risk factors (PAR% 25.3%) and lifestyle risk factors (PAR% 24.6%) in participants aged 40-<55 years, with unhealthy diet and diabetes being the main risk factors. While in participants aged >= 55 years, most deaths were attributed to lifestyle risk factors (PAR% 26.6%-41.0%) and socioeconomic and psychosocial risk factors (PAR% 26.1%-27.7%). In participants aged >= 75 years, lifestyle risk factors accounted for 41.0% of the PAR% for mortality, with inappropriate sleep duration being the leading risk factor. Interpretation: We identified age-specific modifiable risk profiles for CVD and all-cause mortality in Chinese adults, with remarkable differences between adults aged >= 75 years and their younger counterparts. Funding: National Natural Science Foundation of China. (C) 2021 The Author(s). Published by Elsevier Ltd.