Objectives: With the rapid global increase in the age of workforces, companies are increasingly concerned with improving the working conditions of older workers. Anxiety is an important psychological variable in sociological studies but has attracted less attention in studies of occupational health and management. In this study, we explored the mediating effect of anxiety on the relationship between job stressors and presenteeism, and the moderating effect of pessimism. Methods: We collected longitudinal data from 892 respondents who participated in the 2008 and 2012 waves of the Health and Retirement Study in the United States. We tested the proposed moderated mediation model using structural equation modeling. Results: Job stressors were positively related to anxiety and presenteeism. Anxiety was positively related to presenteeism and mediated the relationship between job stressors and presenteeism. Pessimism had a statistically significant negative effect on the relationship between anxiety and presenteeism. Conclusions: These results make theoretical and practical contributions to the literature on the influencing mechanisms of presenteeism. The use of longitudinal data ensured that the research conclusions were reliable; we suggest ways to improve the productivity of aging workers.