BACKGROUND: Effective models of support for HIV pre-exposure prophylaxis (PrEP) are needed for populations at elevated risk. In a hyperendemic Ugandan fishing community, PrEP counseling was provided through a situated Information, Motivation, and Behavioral Skills (sIMB)-based community health worker (CHW) intervention. We evaluated the intervention using a mixed-methods, implementation science design. METHODS: We surveyed all community members aged 15-49 through the Rakai Community Cohort Study. We used multivariable logistic regressions with generalized estimating equations to estimate the intervention's effect on PrEP knowledge and utilization. To understand intervention experiences and mechanisms, we conducted 74 qualitative interviews with 5 informant types (clients, CHWs, program staff, community leaders, health clinic staff) and analyzed data using an iterative, deductive approach. A mobile phone application provided intervention process implementation data. RESULTS: Individuals self-reporting receipt of the CHW intervention showed significantly higher PrEP knowledge (N = 1848, PRR: 1.10, 95% CI: 1.06-1.14, = <.0001), PrEP ever use (N = 1176, PRR: 1.77, 95% CI: 1.33-2.36, = <.0001), and PrEP current use (N = 1176, PRR: 1.86, 95% CI: 1.22-2.82, p = 0.0039) compared to those who did not. Qualitative findings attributed positive PrEP outcomes to CHW counseling and effective use of motivational interviewing skills by CHWs. Salient themes across the RE-AIM framework included support for the CHW intervention and PrEP across clients, community, and implementers. Mobile application data demonstrated consistent delivery of the PrEP module throughout implementation. CONCLUSIONS: CHWs improved PrEP knowledge and use among clients in an HIV hyperendemic fishing community. Mixed-methods, implementation science evaluations can inform adaptation of similar PrEP implementation strategies.