This study explored the extent to which county- and individual-level factors were associated with awareness, willingness to use, and use of pre-exposure prophylaxis (PrEP) among US men who have sex with men (MSM). We conducted multilevel analyses using a sample of 8338 MSM residing in 1257 US counties drawn from the 2014–2015 American Men’s Internet Survey to examine these associations, with focuses on variation in PrEP outcomes across counties and proportion variation explained by county-level factors (HIV prevalence, racial composition, median household income, income inequality, health insurance coverage). Results showed that PrEP awareness varied moderately across counties (intraclass correlation coefficients [ICC] = 7.7%), willingness to use did not vary; however, the actual use varied substantially (ICC = 20.7%). Half of the variation in awareness and use was explained by county-level factors. Higher median household income was associated with greater likelihood of awareness and use. Higher income inequality was associated with greater likelihood of PrEP awareness. Findings can inform the development of multilevel interventions to address PrEP uptake among MSM and identify communities where structural intervention is most needed.