The aim of this cross-sectional study was to compare the rates of mental disorders, sexual dysfunctions and childhood maltreatment (CM) in women with endometriosis with either chronic pelvic pain (CPP) or minimal to no pelvic pain. Additionally, two models to predict a current mental disorder were tested, including pelvic-pain-related or psychosocial predictor variables. We examined 100 women with confirmed endometriosis (group CPP, n = 50; group NOPAIN, n = 50). Participants responded to a comprehensive questionnaire and the Childhood Trauma Questionnaire. The Diagnostic Interview for Mental Disorders was used to assess mental disorders according to DSM5 and to screen for sexual dysfunctions. The mean age was 28.8 ± 5.6 (CPP)/ 2.7 ± 6.3 (NOPAIN). Participants with CPP had higher rates of current mental disorders (p = 0.019), lifetime mental disorders (p = 0.006) and sexual dysfunctions (p < 0.001), but not CM (p = 0.074). In two binary-logistic regression analyses, a greater need for pain relief (aOR = 4.08, p = 0.026) and a sexual dysfunction (aOR = 2.69, p = 0.031) were significant predictors for a current mental disorder. Our findings confirmed the crucial role of pelvic pain for mental and sexual well-being in endometriosis. They highlight the need for pain relief and interdisciplinary care in the treatment of endometriosis.