The influence of pain catastrophizing, kinesiophobia and fear-avoidance attitudes towards non-specific low-back pain has been scarcely studied in an occupational insurance provider context. The objective of this work is to ascertain the relationship between these psychosocial variables with work absence, its duration and the disability of subjects with work-related low back pain. This is a descriptive observational methodological strategy. All patients with work-related non-specific low back pain who attended to an occupational health hospital during the study period were included consecutively. Clinical variables of kinesiophobia, pain catastrophizing, fear-avoidance attitudes, disability and pain were collected; sociodemographic variables of sex, age, type of work, educational level, occupational status and duration in days of work absence were recorded. Kinesiophobia (b = 1.43, P = 0.011, r = 0.333), fear-avoidance beliefs in its global dimension (b = 0.910, P = 0.014, r = 0.321), fear-avoidance beliefs in its work dimension (b = 1.255, P = 0.016, r = 0.321) and pain catastrophizing (b = 0.997, P = 0.013, r = 0.340) show individual association with the duration of sickness absence. Kinesiophobia (b = 0.821, P = 0.011, r = 0.30) and fear-avoidance beliefs (b = 1.760, P = 0.016, r = 0.28) are associated with disability (Kinesiophobia, b = 0.880, P = 0.045, r = 0.26; Fear-avoidance beliefs, b = 0.724, P = 0.010, r = 0.34). Kinesiophobia, fear-avoidance beliefs and pain catastrophizing are related to an increase in the duration of work absence and disability in patients with back pain in an occupational insurance provider context.