There is a need to understand which factors are associated with sickness absence in the context of public service in order to guide efforts to prevent illness in workers. We investigated whether lifestyle, locus of health control, work-related stress, and self-perception of physical and mental health are associated with sickness absence from a biopsychosocial perspective. This is a cross-sectional study using an online questionnaire and the participants comprised 898 employees at a federal university. The assessment included instruments on sociodemographic and occupational characteristics, sickness absence, lifestyle (FANTASTIC Lifestyle scale), locus of control (Multidimensional Health Locus of Control Scale), workrelated stress (Health Safety Executive), and physical and mental health (Short-Form Health Survey 12 - version 2). A Poisson regression model was constructed using Generalized Estimating Equations to identify the variables associated with sickness absence, with a p ≤ 0.05 significance level. We found that work-related stress, locus of control, physical and mental health, administrative or technical job role, female gender, and longer service time at the institution were associated with a higher number of days absent from work due to illness (for all associations, p < 0.001). The present study contributes to the literature by offering additional data on sickness absence in the context of Brazilian public university employees.