BACKGROUND: Transgender women (TGW) are disproportionately impacted by sexually transmitted infections (STIs). To date few studies have been done of STIs in TGW from Latin America. We sought to estimate the prevalence of human immunodeficiency virus (HIV), human papillomavirus (HPV), hepatitis B and C, syphilis, gonorrhea, and chlamydia among TGW in Cali, Colombia. METHODS: We conducted a cross-sectional study using respondent-driven sampling (RDS) between May and November 2023. Eight TGW seeds initiated recruitment chains. Eligible participants completed a survey, underwent a physical examination, and were tested for STIs, including pooled swabs for HPV, chlamydia, and gonorrhea. Network size-adjusted prevalence estimates with their corresponding 95% confidence intervals (95% CI) were calculated using RDS-II weighting. RESULTS: A total of 169 TGW were enrolled. Median age was 39 years, 69% reported engaging in transactional sex in the past year and 68% reported condomless sex during their last encounter. Only 50% had been tested for any STIs in the past year. Adjusted prevalence estimates were 45.8% (95% CI 31.9-59.6) for HIV, 41.3% (95% CI 27.0-55.7) for high-risk HPV, 16.9% (95% CI 3.7-30.1) for gonorrhea, 15.5% (95% CI 3.9-27.1) for chlamydia, 14.8% (95% CI 6.9-22.6) for presumptive active syphilis, 4.6% (95% CI 0-10.1) for hepatitis B, and 1.7% (95% CI 0-3.4) for hepatitis C. Approximately 40% had multiple infections. Most cases of chlamydia and gonorrhea were asymptomatic. CONCLUSIONS: STIs are highly prevalent among TGW in Cali. These findings highlight the urgent need for expanded diagnostic capacity and community-centered interventions to improve sexual health among TGW.