Background Some migrant men who have sex with men (MSM) acquire HIV in France. Aims We investigated, in migrant MSM receiving HIV care in France, the (i) rate of post-migration-HIV acquisition in France, (ii) delay between arrival and HIV acquisition and (iii) factors affecting HIV acquisition within 1 year after migration. Methods This cross-sectional study focused on ≥ 18-year-old MSM born outside France, receiving HIV care in the Paris region. Information on migration history, socioeconomic condition, sexual activity, and health was collected in May 2021–June 2022 through self-administered questionnaires and medical records. Post-migration-HIV-acquisition rate and delay between arrival in France and HIV acquisition were estimated from biographical data and CD4 + T-cell counts. Predictors of HIV acquisition within 1 year after migration were determined using logistic regression. Results Overall post-migration HIV-acquisition rate was 61.7% (715/1,159; 95%CI: 61.2–62.2), ranging from 40.5% (95%CI: 39.6–41.6) to 85.4% (95%CI: 83.9–86.0) in participants from Latin America and North Africa. Among post-migration-HIV acquisitions, those within 1 year after migration represented 13.1% overall (95%CI: 11.6–14.6), being highest in participants from sub-Saharan Africa (25%; 95%CI: 21.5–28.3). Participants ≥ 15-years old at migration, with post-migration-acquired HIV, had a 7.5-year median interval from arrival in France to HIV acquisition (interquartile range (IQR): 3.50–14.75). Older age at arrival, region of origin (sub-Saharan Africa and Asia), degree of social disadvantage and numbers of sexual partners were independently associated with acquiring HIV within 1 year in France. Conclusion Our findings may guide HIV prevention policies for most vulnerable migrants to Europe.