State-level structural stigma and its consequences in healthcare settings shape access to pre-exposure prophylaxis (PrEP) for HIV prevention among gay, bisexual, and other men who have sex with men (GBMSM). Our objective was to assess the relationships between same-sex marriage laws, a measure of structural stigma at the state level, provider-patient communication about sex, and GBMSM awareness and use of PrEP. Using data from the Fenway Institute's MSM Internet Survey collected in 2013 (N = 3296), we conducted modified Poisson regression analyses to evaluate associations between same-sex marriage legality, measures of provider-patient communication, and PrEP awareness and use. Living in a state where same-sex marriage was legal was associated with PrEP awareness (aPR 1.27; 95% CI 1.14, 1.41), as were feeling comfortable discussing with primary care providers that they have had sex with a man (aPR 1.63; 95% CI 1.46, 1.82), discussing with their primary care provider having had condomless sex with a man (aPR 1.65; 95% CI 1.49, 1.82), and discussing with their primary care provider ways to prevent sexual transmission of HIV (aPR 1.39; 95% CI 1.26, 1.54). Each of these three measures of provider-patient communication were additionally associated with PrEP awareness and use. In sum, structural stigma was associated with reduced PrEP awareness and use. Policies that reduce stigma against GBMSM may help to promote PrEP and prevent HIV transmission.