Research suggests that having a sexually transmitted infection (STI) such as genital herpes and human papillomavirus (HPV) can negatively affect sexual well-being. However, there is little research examining factors associated with poorer sexual well-being among individuals with a STI. This study investigated the extent to which stigma experiences, individual characteristics, and STI characteristics were associated with multiple aspects of sexual well-being among individuals diagnosed with herpes and/or HPV. Participants were an average of 36 years old (SD = 11.58) and included 188 individuals with herpes and/or HPV who completed measures of sexual activity, sexual problems, and sexual cognitive-affective factors. The results showed that experiences of stigmatization were the most important predictors of sexual well-being. Participants who perceived were stigmatized by others as well as those who internalized negative social attitudes to a greater extent reported poorer sexual well-being across all dimensions, over and above individual and STI characteristics. The implications of these findings for sexual health professionals are discussed.