This study examined the associations between the complexity of an individual’s primary lifetime occupation and his or her late-life memory and reasoning performance, using data from 824 community-dwelling participants aged 69–72 years. The complexity of work with data, people, and things was evaluated based on the Japanese job complexity score. The associations between occupational complexity and participant’s memory and reasoning abilities were examined in multiple regression analyses. An association was found between more complex work with people and higher memory performance, as well as between more complex work with data and higher reasoning performance, after having controlled for gender, school records, and education. Further, an interaction effect was observed between gender and complexity of work with data in relation to reasoning performance: work involving a high degree of complexity with data was associated with high reasoning performance in men. These findings suggest the need to consider late-life cognitive functioning within the context of adulthood experiences, specifically those related to occupation and gender.