Drawing on hospital-based interviews and fieldwork in a deprived Parisian suburb, this paper analyses the spatio-temporal dynamics of risk, exposure, and mobilities in individual stories of undocumented Pakistani male migrants, and asylum seekers—receiving treatment for single and combined diagnoses of HIV, and Hepatitis C and B. Inviting alignments with the ‘sexual’ turn in mobility studies, it prioritises the interface of all-male undocumented migration, mobility, sexuality, and homosociality in circumscribing disease transmission geneaologies. It questions the extent to which illegal migration routes are transmission routes, and risk environments assume different levels of intensity in everyday life in Pakistan, during the journey, and in France. It emphasises inadequately addressed epidemics of HIV and hepatitis in Pakistan, the significance of unequal routes to migrant healthcare in France, and the transnational adaptation of homosocial and sexual behaviours, including MSM. These factors interplay with intensified vulnerabilities relating to childhood sexual abuse, family traumas, sexual risks related to illegal migration and undocumented status in France, chronic stresses leading to depleted mental and physical health, and restrictions on heterosexual sex facing marginalised migrants. Further, temporal vulnerabilities relate to the colonial criminalisation of homosexuality in Pakistan, widespread sexual violence—and forms of contemporary exclusion and hostility regarding Muslim migrants in Europe. Particularly, we emphasise the paradox, and need to sensitively address, a complex confluence of hidden risks that are deeply embedded in ethnic communities of solidarity and support. The findings trouble the tendency to partition global hepatitis and HIV prevalence rates by ‘developed’ and ‘developing’ country variation.