Abstract Background To explore the association of sedentary time with cardiocerebral deaths. Methods A total of 12,608 community residents aged 35 years or above in Jiangxi Province who took part in “the study on prevalence of major cardiovascular diseases and key techniques in China” during 2013–2014 were enrolled in this prospective, observational cohort study. Sedentary time was obtained through baseline questionnaire, and all death events were collected by telephone follow-up, information report from the departments of public health in township health centers and village doctors, and death surveillance system of Jiangxi Center for Disease Control and Prevention. Cox proportional hazard regression model was used to evaluate the association of sedentary time with cardiocerebral deaths. Results A total of 11,744 participants were included in final analysis. During an average 5.4 years of follow-up (63,298 person-year), 796 all-cause deaths occurred, including 373 cardiocerebral deaths. The difference of cardiocerebral death rate was statistically significant in 3 groups of <6 h/d (2.9%), 6–8 h/d (3.9%), and >8 h/d (5.4%). Kaplan–Meier curve showed that there was a significant difference in the cumulative mortality among the 3 groups (log rank χ2 = 17.27, P < 0.01). Cox regression analysis showed that after adjusting for relevant confounding factors, older age, high diastolic pressure and body mass index, male, country of residence, unemployment, and long sedentary time were risk factors for cardiocerebral deaths. Compared with the <6 h/d group, the risk of cardiocerebral deaths increased by 68.3% (HR = 1.683, 95% CI: 1.186–2.388) for participants with sedentary time of >8 h/d. Conclusions Long sedentary time independently increases the risk of cardiocerebral deaths.