Objective Community health worker (CHW)-led education is an important strategy to increase awareness and access to breast cancer screening in medically-underserved communities. This study aimed to develop a context-specific, culturally-appropriate training intervention for South Florida CHWs to educate Latinx immigrant farmworkers on breast cancer and early detection. Methods A community-based participatory research (CBPR) study, conducted 2017-2019, informed the design of a training curriculum for CHWs and educational dissemination materials. Twenty-two CHWs were trained and knowledge gains were measuring using a one-group pre-and post-test design. Triangulated evaluation consisted of field observations of CHW-client interactions, CHW self-reports, and rapid assessment surveys of community members. Results A community stakeholder-informed breast cancer training curriculum resulted in significant, sustained breast cancer knowledge gains among CHWs when comparing pre-, post-, and 4-6 month post-training follow-up test scores. Field observations of educational material dissemination, CHW self-reported evaluations, and community rapid assessment surveys at three health fairs demonstrated this was an effective strategy to engage female Latinx farmworkers in breast cancer education. Conclusions Community and key stakeholder participation in the development of a breast cancer educational intervention allowed for tailored design priorities around knowledge-based content, comprehensiveness, relevance, appropriateness, and ease of dissemination to community members. This model of participatory CHW training intervention design can enable future train-the-trainer approaches to disseminate and scale-up evidence-based health education interventions.