Job satisfaction has gained increasing interest in the world of work and a vast field of research has been stimulated regarding its antecedents. Among these, personality traits have received consistent and significant attention, with a particular emphasis on conscientiousness. To delve deeper and detail these aspects, in the present research, a moderation model was hypothesized, with the aim of investigating the effect of age on the association between conscientiousness (and its subdimensions scrupulousness and perseverance) and job satisfaction. The age-moderated interactions of the other Big Five personality traits were also explored. The study involved 202 Italian workers (92 men, 110 women) with a mean age of 44.82 years (SD = 10.56) who completed the Big Five Questionnaire and the Job Satisfaction Scale. The results showed a positive association between conscientiousness and job satisfaction. This was moderated by age to the extent that it was significant for younger and average-age workers and was less significant for older workers. Similar results were found for the subdomain of perseverance, while the relationship between scrupulousness and job satisfaction was not significant. Furthermore, no age-moderated interaction between the other Big Five personality traits and Job satisfaction were found. Such data supports interactive models that highlight the need to integrate personality traits with other factors in exploring the antecedents of job satisfaction. These findings provide additional elements to an understanding of the factors contributing to workers satisfaction, and could have important applicative implications in a framework for healthy organizations and the well-being movement.