BACKGROUND: There is a high incidence of HIV among young sexual minority men in Florida. Many are unaware of their status due to low testing rates. Counseling, testing, and referral (CTR) services are essential for diagnosis and prevention of HIV and are integral to the Ending the HIV Epidemic (EHE) strategic plan. However, efforts to increase CTR among young sexual minority men have not been successful. OBJECTIVE: The Young Adult Centered Healthforce Training (YACHT) program promotes developmentally sensitive, culturally appropriate, and evidence-based CTR services for young sexual minority men. This study tests whether the YACHT program increases HIV testing among young sexual minority men and fidelity to evidence-based CTR among testing providers. METHODS: Agencies in Florida EHE counties that tested at least 24 young sexual minority men aged 18 to 29 years in 2021 will be invited to participate. The sites (N=42) will be randomized in blocks of 6 to participate in the YACHT program, following a stepped wedge design. Through YACHT, all sites will receive visits from mystery shoppers (MSs), who are trained to evaluate HIV testing services and complete postvisit quality monitoring assessments. Sites will be offered the opportunity to review their MS feedback and to receive tailored motivational interviewing training and evidence-based technical assistance to address areas of need identified through MS assessments. The study will evaluate whether YACHT leads to increased HIV testing by comparing numbers of young sexual minority men testing for HIV before versus after YACHT's implementation. The Exploration, Preparation, Implementation and Sustainment framework will help understand the barriers to and facilitators of the program's implementation and sustainment. RESULTS: YACHT was funded in August 2022. Data collection began in June 2023. As of June 2024, 194 MS visits have taken place at 42 sites; 4 (67%) sites from the first block and 1 (33%) site from the second block have engaged with the study. At baseline, sites exhibited the lowest competencies in relationship context, counseling sessions, and safer sex education and the highest competency in privacy and confidentiality. Data collection will continue through May 2027, with results published by the end of 2027. CONCLUSIONS: To address the high incidence of HIV among young sexual minority men in Florida, YACHT aims to support testing sites with tailored motivational interviewing training and technical assistance to address needs identified by MS assessments. The program seeks to improve delivery of evidence-based CTR services, thereby increasing HIV testing, counseling, and pre-exposure prophylaxis referrals and reducing HIV incidence among this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT06015581; https://classic.clinicaltrials.gov/ct2/show/NCT06015581. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/63191.