Objectives: Socioeconomic position (SEP) in childhood predicts cardiovascular health in adulthood but the underlying mechanisms remain unclear. Using a longitudinal study design, we examined the extent to which adult SEP acts as a pathway (mediator) connecting childhood SEP with adult cardiovascular health, and if upward social mobility mitigates the health-effects of early low SEP. Method: The sample comprised 697 participants from a prospective Finnish cohort followed during 32 years. Childhood SEP was assessed from the parents in 1980 (participant mean age 10.9) and adulthood SEP was examined in 2007 and 2012 (participant mean age 43.2 in 2012). Both childhood and adulthood SEP scores comprised education, income, occupational status, and occupational stability. Ideal cardiovascular health was assessed in 2007 and 2012 according to the American Heart Association’s guidelines. Results: Higher childhood SEP was associated with higher ideal cardiovascular health index in adulthood (β = 0.13, p < .001) independently of sex, age, childhood cardiovascular risk factors, and chronic conditions. Mediation analysis showed that adult SEP accounted for 33% of the association between childhood SEP and ideal cardiovascular health index. Upwardly mobile participants scored higher on ideal cardiovascular health in adulthood compared with participants staying in lower SEP (M = 4.05 vs. 3.56, p < .001). Conclusions: Transmission of SEP over generations is a predictor of health inequalities, which should be considered in cardiovascular prevention. Although upward social mobility mitigates some of the effect of early SEP disadvantage on later cardiovascular health, childhood SEP remains an important predictor of future health.