ABSTRACT Proximal minority stressors (e.g. internalised homonegativity, motivation to conceal a sexual minority identity) have severe adverse effects on sexual minority individuals’ mental health. Many sexual minorities report experiencing workplace harassment, which is linked to poorer mental health outcomes. However, the precise nature of how workplace harassment shapes the relationship between minority stress and mental health is unknown. To address this question, we tested the moderation effect of workplace harassment on the relationship between proximal minority stressors, specifically internalised homonegativity and concealment motivation, and psychological distress (i.e. depression, anxiety, somatisation) using Hayes’ PROCESS macro package in SPSS. Sexual minority employees living in the United States (N = 529) completed a survey involving measures of proximal minority stressors, workplace harassment, and psychological symptoms via Prolific. Results of the moderation analyses supported the hypothesis that workplace harassment amplifies the positive relationship between internalised homonegativity and anxiety symptoms as well as the relationship between internalised homonegativity and somatic symptoms, though a similar moderation effect was not found for depression. We did not find a significant moderation effect of workplace harassment on the link between concealment motivation and psychological symptoms. We conclude by emphasising the importance of creating safer workplace environments for sexual minorities and identifying directions for future research.