Visceral leishmaniasis (VL) patients with HIV co-infection should receive antiretroviral treatment (ART). However, the best timing for initiation of ART is not known. Among such individuals, we assessed the influence of ART timing on VL outcomes. A retrospective cohort study was conducted in Northwest Ethiopia among VL patients starting ART between 2008 and 2015. VL outcomes were assessed by the twelfth month of starting ART, within 4 weeks of VL diagnosis or thereafter. Of 213 VL-HIV co-infected patients with ART initiation, 96 (45.1%) had moderate to severe malnutrition, 53 (24.9%) had active TB and 128 (60.1%) had hemoglobin levels under 9 g/dL. Eighty-nine (41.8%) were already on ART before VL diagnosis, 46 (21.6%) started ART within 4 weeks, and 78 (36.6%) thereafter. Definitive cure in those starting ART within 4 weeks 59% (95% CI 43-75%) and those starting thereafter 56% (95% CI 44-68%) was not significantly different. Those starting ART before primary VL had higher 12-months mortality compared to those starting later (RR 0.6; 95% CI 0.4-0.9; p=0.012). VL-HIV patients are severely ill and with serious additional comorbidities. Outcomes of HIV-VL management are unsatisfactory and early ART initiation was associated with higher mortality. Further research on the optimal timing of ART initiation, and ensuring earlier diagnosis of VL patients, with improved management of comorbidities are needed.