Racial, ethnic, and socioeconomic disparities in pain severity and treatment persist across healthcare settings, reflecting inequities shaped by patients' experiences of discrimination and bias. Perceived healthcare discrimination (PHCD), feeling dismissed, disrespected, or treated unfairly by healthcare providers, may contribute to persistent pain disparities among socially disadvantaged populations, yet its independent role relative to everyday discrimination remains underexplored. Using cross-sectional data from the All of Us Research Program, we examined associations between PHCD and pain severity among 89,069 participants from the Registered Tier Dataset (v7, R2022Q4R9), excluding individuals with missing data or non-categorized racial identities. Multinomial logistic regression models adjusted for age, sex, race/ethnicity, income, and education were used to estimate odds ratios (ORs) for pain severity. Both occasional and frequent PHCD were significantly associated with higher odds of mild, moderate, and severe pain (all p <.001). Participants reporting frequent PHCD had nearly eightfold higher odds of severe pain compared with those reporting no discrimination (OR = 7.98, 95% CI: 6.85-9.30). These associations persisted after full covariate adjustment, demonstrating a clear dose-response relationship between discrimination frequency and pain severity. PHCD emerged as a robust and independent predictor of pain severity in a large, diverse national sample, highlighting discrimination as a modifiable social determinant of pain and underscoring the need for equity-focused clinical communication and systemic interventions to improve pain management. PERSPECTIVE: This study, the largest to date examining perceived healthcare discrimination, demonstrates a significant association with greater pain severity across diverse populations. Highlighting a critical social determinant of health, these findings underscore the importance of addressing discrimination within clinical care. Integrating equity-focused strategies into pain assessment and management is essential to reduce disparities and improve outcomes among marginalized communities.