Patient-nominated supporters can potentially improve the continuum of HIV care. We retrospectively determined factors associated with having a patient-nominated supporter among people living with HIV (PLWH), and its association with retention in care and viral suppression. We analysed registries of adults evaluated by social workers (n = 1345) at a referral hospital in Peru between 2011–2014. Nondisclosure of HIV status was associated with lacking supporters (aPR: 5.41, 95% CI: 3.83–7.64). Retention in care was 76.4% and 34.2% after one and two years of enrolment, respectively. PLWH with supporters were more likely to be retained in care after two years (aRR = 1.36, 95% CI: 1.02–1.81), but not after one year (aRR = 1.10, 95% CI: 0.98–1.23) compared to PLWH without supporters. Having supporters who were parents or friends was associated with an increased probability of being retained in care after one and two years of enrolment. Viral suppression after one year of enrolment was 58.7%. Having a supporter was not associated with viral suppression (aRR = 1.18, 95% CI: 0.99–1.41), but PLWH with supporters were more likely to have viral load measurements (p = 0.005). Patient-nominated supporters appear beneficial for engagement in HIV care; these benefits may be related to the nature of their relationship with PLWH.