BACKGROUND: Our objective was to estimate for the first time the prevalence and determinants of human immunodeficiency virus type 1 (HIV-1) and sexually transmitted infections (STIs) among male migrants in India. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a multi-stage stratified probability sample survey of migrant (defined as not born in Surat city) men aged 18 to 49 years working in the diamond and textile industries in Surat city. Behavioural and biological data were collected. Biological data included laboratory diagnosed herpes simplex virus type 2 (HSV-2), syphilis, chlamydia, gonorrhoea, Trichomonas vaginalis (together defined as 'any STI') and HIV-1. Likely recently acquired STIs included chlamydia, gonorrhoea, T. vaginalis and syphilis with rapid plasma reagin ≥1:8. The response rate was 77% (845/1099). Among 841 participants, HIV-1 prevalence was 1.0%, 'any STI' prevalence was 9.5% and 38.9% of these STIs were likely to have been recently acquired. Being a diamond worker, Surat resident for 10+ years and recent antibiotic use were each associated with higher odds of 'any STI' (aORs 1.83 (95% CI 1.09-3.09), 1.98 (95% CI 1.22-3.22) and 2.57 (95% CI 1 .17-5.64), respectively) after adjusting for the other two factors and age. The main study limitation was social desirability bias for self-reported sexual behaviour; STIs were diagnosed in some self-reported virgins. CONCLUSIONS/SIGNIFICANCE: HIV and STI prevalence were lower than expected, but prevention interventions remain necessary in Surat since almost 40% of STIs among participants were probably recently acquired and sentinel surveillance HIV prevalence remains high. The participants had a similar HIV prevalence to Surat antenatal clinic attendees, a proxy for the general population. This suggests migrants are not always at higher risk of HIV compared to the general population in their migration destination. Our findings highlight the need to contextualise research findings from a specific setting with other local information to guide HIV/STI prevention interventions.