OBJETIVE: To identify recent HIV-1 infection and estimate HIV incidence among adolescent men who have sex with men (AMSM) and transgender women (ATGW) in Brazil. METHODS: From January to December 2020, a cross-sectional analysis was conducted with baseline data from the PrEP1519 study, an HIV pre-exposure prophylaxis (PrEP) demonstration cohort in Brazil among sexually active AMSM/ATGW aged 15–19. For enrollment, participants were screened with a fourth-generation HIV rapid test. The recent infection testing algorithm (RITA) included a recency assay in blood specimens, viral load, and CD4 cell count prior to antiretroviral treatment use. Among these participants, RITA-based HIV incidence was estimated using a mean duration of recency infection of 214 days and a false-recent rate of 0.02. RESULTS: Out of the 494 participants screened, 21 tested positive for HIV. Following RITA, five adolescents had a recent HIV infection, 14 had long-term infections, and two did not have blood specimens available. We classified these two participants as long-term infection cases due to CD4 cell counts and previous use of antiretroviral treatment. Among those who tested positive, all but one were AMSM (94.7%), 73.6% were aged 18–19, and 76.2% were non-White. The HIV prevalence was 4.2%, and the estimated HIV incidence was 1.7%. CONCLUSIONS: The estimated incidence highlights the need for targeted HIV prevention interventions, such as PrEP, for sexual minority adolescents. Integrating RITA into routine HIV testing services for this population provides valuable information on the current HIV epidemic. This strategy can aid in monitoring the effectiveness of prevention efforts and improving early entry to HIV care.