Objective Emotional adjustment to cancer survivorship may be influenced by how patients interpret treatment side effects and other cancer-related experiences. The current study examined cognitive representations of illness, as conceptualized by the Self-Regulatory Model (SRM), in men treated for localized prostate cancer (PC). More severe PC perceptions were hypothesized to predict poorer emotional well being, particularly among men experiencing greater post-treatment sexual dysfunction or general life stress. Methods The Perceived Stress Scale, Expanded Prostate Cancer Index Composite, Illness Perception Questionnaire-Revised, and Functional Assessment of Cancer Therapy were administered to 214 men within 18 months of completing treatment for early stage PC. Results Perceptions that PC was less comprehensible, was less likely to be controlled by treatment, and was more likely caused by one's own personality and behaviors remained associated with poorer emotional well being after adjusting for relevant medical and demographic factors. Life stress moderated the relationship between perceived consequences of PC and emotional well-being, such that more severe perceptions of negative consequences predicted poorer emotional well-being only for men experiencing higher life stress. Degree of sexual dysfunction did not moderate any relationships between cancer perceptions and emotional well-being. Conclusion Within 18 months of completing treatment for localized PC, more severe perceived consequences of PC were associated with poorer emotional well-being, particularly among men experiencing greater life stress. Interventions that target distortions in illness perceptions may enhance emotional adjustment among the most distressed PC survivors.