<b><i>Introduction:</i></b> The role of risk factor profile in childhood and adolescence on adulthood cognitive function and whether it differs by genetic risk is still obscure. To bring this evidence, we determined cognitive domain-specific youth risk factor profiles leveraging the childhood/adolescence data from the Cardiovascular Risk in Young Finns Study and examined whether genetic propensity for poor cognitive function modifies the association between the risk profiles and adulthood cognitive function. <b><i>Methods:</i></b> From 1980, a population-based cohort of 3,596 children (age 3–18 years) has been repeatedly followed up for 31 years. Computerized cognitive test measuring (1) memory and learning, (2) short-term working memory, (3) reaction time, and (4) information processing was performed for 2,026 participants (age 34–49 years). Cognitive domain-specific youth risk profile scores, including physical and environmental factors, were assessed from the data collected at baseline and categorized into favourable, intermediate, and unfavourable. A polygenic risk score for a poor cognitive function was categorized into low, intermediate, and high risk. <b><i>Results:</i></b> At all genetic risk levels, a favourable youth risk factor profile is associated with better learning and memory, short-term working memory, and information processing compared to unfavourable risk profile (e.g., β = 0.501 SD, 95% CI: 0.043–0.959 for memory and learning among participants with high genetic risk). However, no significant interactions were observed between the youth risk factor profile score and genetic propensity for any cognitive domain (<i>p</i> &#x3e; 0.299 for all). <b><i>Conclusion:</i></b> A favourable youth risk factor profile may be beneficial for cognitive function in adulthood, irrespective of genetic propensity for poor cognitive function.