More complex occupations during adulthood may be associated with better cognition in later life. We used data from the Brazilian Longitudinal Study of Aging (ELSI) and the Mexican Health and Aging Study (MHAS) to investigate the association between occupational complexity and cognitive function. Using a regression-based approach, participants were classified as cognitively impaired or not. Occupation was categorized into four levels using the 2008 International Standard of Classification of Occupations. We used logistic regression models for separate and pooled analysis. The odds of cognitive impairment decreased with higher occupation skill levels in the ELSI, but this trend was not seen in the MHAS, where the highest skill level was not associated with cognitive impairment. ELSI participants had a lower probability of cognitive impairment compared to MHAS participants with the same occupation skill level. The results of this study suggest that programs addressing the negative consequences of lower-complexity occupations need to be tailored to specific regional contexts, considering their unique socioeconomic, cultural, and occupational landscapes.