HIV infection is a significant public health concern, particularly among young men who have sex with men (YMSM). Pre-exposure prophylaxis (PrEP) is highly effective in preventing HIV infection among YMSM when taken as prescribed. However, there may be unintended behavioral consequences associated with PrEP initiation, with previous studies finding associations between PrEP use and increased sexual risk behaviors such as condomless anal sex (CAS). Further, problematic alcohol use, to which YMSM are particularly vulnerable, may also play a role in increasing sexual risk as engaging in sexual behaviors while under the influence of alcohol has been associated with CAS and other sexual risk behaviors. Previous literature has proposed risk compensation theory as a basis for this change in sexual risk behaviors following PrEP initiation. However, results have been mixed, and fewer studies have examined risk compensation specifically among YMSM or explored the role of alcohol-related sexual behaviors in this relationship. The present study aims to examine risk compensation theory as a mechanism for the relationship between PrEP initiation and alcohol-related sexual behaviors among YMSM. We hypothesized that the trajectory of PrEP initiation would be positively associated with alcohol-related sexual behaviors across 18 months. Consistent with hypothesis, a combined latent difference score and latent trajectory model revealed a positive association between PrEP initiation and alcohol-related sexual behaviors between baseline and 18-month follow-up in a sample of YMSM. These results are consistent with previous research identifying a high-risk period following PrEP initiation among an already vulnerable group (YMSM), with implications for risk assessment and interventions targeting alcohol-related sexual behaviors among YMSM. This study also highlights the role of alcohol use in increasing sexual risk following PrEP initiation. Findings may aid in reducing adverse sexual outcomes among YMSM who initiate PrEP and ultimately contribute to the minimization of sexual health disparities among YMSM.