Purpose <p>Workers’ compensation claims processes may exacerbate mental health symptoms for individuals with work-related mental health conditions (WR-MHCs). This study examined associations between mental health outcomes and contemporaneous claim status.</p> Methods <p>Data of this cohort study were drawn from 153 general practice patients with WR-MHCs providing 422 observations, enrolled in the IMPRovE trial across Australia. Workers’ compensation claim status (accepted, rejected, being assessed, or no claim), working status, and mental health outcomes (Depression Anxiety Stress Scale–21 (DASS-21) and Short-form health survey) were assessed via 3-monthly surveys. Mixed-effects linear regression models were used to assess the relationship between claim status and outcomes, adjusting for intervention status, working status, time-point, state, clinic size, location, age, and gender.</p> Results <p>On the DASS-21, patients with a claim application being assessed reported significantly poorer overall mental health outcomes than those with accepted claims (e.g. stress: <i>β</i> = 5.73, 95% CI 1.69–9.77), rejected claims (e.g. depression: <i>β</i> = 5.88, 95% CI 1.12–10.63), or no claim (e.g. overall mental health: <i>β</i> = 6.14, 95% CI 2.87–9.42). No significant differences were found between patients with accepted, rejected, or no claim.</p> Conclusion <p>In this cohort, poorer mental health outcomes were observed amongst individuals with work-related mental health conditions whose workers’ compensation claims were being assessed, compared with other claim statuses. No differences were observed between accepted, rejected, or no-claim groups. These findings indicate that the adjudication phase of the claims process may be particularly challenging for some individuals and warrant targeted clinical and system-level attention. Further research is needed to establish causality and design interventions that can address causal mechanisms.</p>