Background: Hidradenitis suppurativa (HS) causes significant physical, social, and psychological burdens. Internalized stigma, acceptance of negative attitudes and stereotypes of society regarding a person’s illness, has not been studied previously in HS. Objectives: The objective of this study was to investigate the internalized stigma state of HS patients and identify the factors affecting it. Methods: This multicenter, prospective, cross-sectional study included 731 patients. Internalized Stigma Scale (ISS), Hurley staging, Physician Global Assessment, Dermatology Life Quality Index (DLQI), Skindex-16, Beck Depression Inventory-II (BDI-II), and Visual Analog Scale (VAS)-pain score were used in the study. Results: The mean ISS value (57.50 ± 16.90) was comparable to the mean ISS values of studies in visible dermatological and various psychiatric diseases. A significant correlation was found between the mean values of ISS and all disease activity scores, quality of life measures, BDI-II, and VAS-pain scores. Obesity, family history, low education and income level, vulva/scrotum involvement and being actively treated are significant and independent predictive factors for high internalized stigma in multivariate analysis. Conclusions: HS patients internalize society’s negative judgements, which may create a profound negative effect on access to health care. Therefore, in addition to suppressing disease activity, addressing internalized stigma is fundamental for improving health care quality.