This study examined the influence of persecutory ideation on counterproductive work behaviour (CWB) among employees in selected Nigerian public organisations. Specifically, it investigated the extent to which dimensions of persecutory ideation—ideas of reference, persecution/threat, mistrust/conspiracy beliefs, and hypervigilance/safety behaviours—predict CWB. A cross-sectional survey design was adopted, and data were collected from 238 employees drawn from selected public organisations in Abuja, Nigeria using stratified random sampling. Standardised instruments, including the Counterproductive Work Behaviour Checklist (CWB-C) and the Green et al. Paranoid Thoughts Scale (GPTS), were used for data collection. Data were analysed using hierarchical multiple regression at the 0.05 level of significance. Results indicated that persecutory ideation significantly predicted counterproductive work behaviour among employees, accounting for 21.7% of the variance in CWB (R² = .217, F = 67.247, p < .001). At the dimensional level, ideas of reference emerged as the strongest and most consistent predictor of CWB across all models (β = .326–.436, p < .001), followed by persecution/threat (β = .158–.223, p < .05). Mistrust/conspiracy beliefs demonstrated a weak and inconsistent effect, becoming a significant negative predictor only at the final stage (β = −.212, p < .05), while hypervigilance/safety behaviours did not significantly predict CWB (β = .162, p > .05). The findings suggest that employees’ suspicious cognitive interpretations of workplace interactions significantly increase the likelihood of deviant behavioural responses. The study concludes that persecutory ideation is an important psychological determinant of counterproductive work behaviour in Nigerian public organisations. It recommends the implementation of employee assistance programmes, stress management interventions, and fair organisational practices to reduce workplace deviance and improve employee well-being and organisational effectiveness.