For the first time, the Prevagay study was conducted in Nice, with the primary objective of estimating HIV prevalence among men who have sex with men (MSM) frequenting gay social venues in that city and describing the characteristics of MSM infected with HIV. The study was conducted using a cross-sectional, anonymous, and random approach among MSM frequenting bars, saunas, and backrooms in Nice, as well as in Lille, Lyon, Montpellier, and Paris. Behavioral data were collected via questionnaire, along with blood samples collected on filter paper. Testing for HIV antibodies was performed by the National HIV Reference Center. Among the positive samples, viral load testing and antiretroviral treatment status were assessed. In Nice, 328 MSM frequenting the 9 venues investigated agreed to participate. Half of them were over 39 years old. More than three-quarters identified as homosexual. Nearly half had had more than 10 sexual partners in the past 12 months. As in other cities, the lack of condom use was significant and more pronounced among HIV-positive MSM. HIV prevalence was estimated at 17.1% [95% CI: 11.8–24.1]. This proportion was similar to that in Paris, Lyon, or Montpellier and significantly higher than in Lille. Among HIV-positive MSM, 90.4% had been diagnosed as such, of whom 96.1% were on antiretroviral therapy. These results support the need to strengthen the promotion of various protection methods as part of a diversified prevention strategy during outreach activities in gay social venues.