Young men who have sex with men (YMSM) under 25 years old are among the few populations with increasing numbers of new HIV infections in parts of the world where HIV incidence is declining overall. In this systematic review, we synthesize the literature on HIV prevalence among MSM in Latin America and the Caribbean focusing on YMSM. Results were stratified according to study population sampling method used (probability and non-probability based). Forty-seven studies from 17 countries were published in the last 10 years. Among studies using probability-based sampling method (N = 21), HIV prevalence among MSM ranged from 1.2 to 32.6%. HIV prevalence tended to increase over time in studies sampling at different time points. HIV prevalence among YMSM exceeded 5.0% in more than a half of studies (51%; N = 22/43). Our review corroborates the high and potentially rising incidence of HIV among YMSM and characterizes the region's greatest challenge to ending the epidemic.