While a growing body of research is examining the impacts of prolonged occupational sitting on cardiovascular and other health risk factors, relatively little work examined the effects of occupational standing. The objectives of this paper were to examine the relationship between occupations that require predominantly sitting, and those that require predominantly standing, and incident heart disease. A prospective cohort study combining responses to a population health survey with administrative health care records, linked at the individual level was conducted in Ontario, Canada. The sample included 7320 employed labour market participants (50% male) working 15 hours a week or more and free of heart disease at baseline. Incident heart disease was assessed using administrative records over an approximately 12-year follow-up period (2003-2015). Models were adjusted for a wide range of potential confounding factors. Occupations involving predominantly standing were associated with an approximately two-fold risk of heart disease compared to occupations involving predominantly sitting. This association was robust to adjustment for other health, socio-demographic and work variables. Cardiovascular risk associated with occupations that involve combinations of sitting, standing and walking differed for men and women, with these occupations associated with lower cardiovascular risk estimates among men, but elevated risk estimates among women.