Perceived job insecurity is associated with poor mental health, but whether it affects sickness absence is not well understood. The present study examines the association between perceived job insecurity and sickness absence due to common mental disorders and whether changes in perceived job insecurity affects the risk of sickness absence due to common mental disorders. Data are from the Swedish Longitudinal Occupational Survey of Health and include those who participated at least once between 2010 and 2020 (n = 24 049). Two different types of analyses were conducted: (1) logistic regression with adjustments for baseline covariates and (2) pooled logistic regression with inverse probability weights, across 5 emulated target trials assessing onsets and/or offsets of job insecurity versus stable security or stable insecurity, on the risk of sickness absence for common mental disorders. Perceived job insecurity was associated with increased odds of sickness absence for common mental disorders over a 2-year period (odds ratio = 1.38, 95% confidence intervals (CI) 1.13-1.68). We found no statistically significant associations for an onset of job insecurity versus being stably secure (risk ratio (RR) 1.484, 95% CI 0.913-2.055) nor for offset versus stable insecurity (RR 0.855, 95% CI 0.308-1.402). The findings from our emulated target trials were, however, uncertain. Findings suggest that perceived job insecurity increases the risk of sickness absence for common mental disorders. The study implies that efforts to increase employee's sense of security may help reduce rates of sickness absence for common mental disorders if job insecurity is reduced long-term.