The Latinx population in the United States is disproportionately affected by HIV. Our community-based participatory research partnership developed, implemented and evaluated a Spanish-language peer navigation intervention designed to increase HIV testing and condom use among social networks of immigrant Spanish-speaking Latinx gay, bisexual and other men who have sex with men (GBMSM) and transgender women (TW). We randomized 21 social networks of Latinx GBMSM and TW, ages 18–55 years, to the intervention, known as HOLA, or a waitlist control group. Social network participants (n = 166) completed structured assessments at baseline and 12-month follow-up (24 months after baseline). Follow-up retention was 95%. Individual in-depth interviews with a sample of participants documented their intervention-related experiences, needs, and priorities to inform future research. At follow-up, HOLA participants reported increased HIV testing (adjusted odds ratio = 8.3; 95% CI = 3.0–23.0; P < 0.0001). All study participants reported increased condom use; there was no significant difference between HOLA and waitlist control participants. In-depth interviews identified critical intervention elements and impacts and community needs and priorities. The HOLA intervention is effective for increasing HIV testing among Latinx GBMSM and TW, an initial step within the HIV prevention and care continua, and may be adaptable to promote pre-exposure prophylaxis uptake.