Emerging evidence suggests financial incentives (FIs) improve medication adherence in select populations. A small proportion of adolescents with perinatal HIV (PaHIV) transfer to adult services with established poor adherence and advanced disease. We describe a single center adherence intervention combining FIs with motivational interviewing (MI). Eligible patients (PaHIV,16-25 years, CD4 count ≤ 200, off ART despite multiple attempts) received MI, and FI dependent on viral load (VL) reduction for 1 year. Outcome measures compared CD4 gain from baseline at 1 year and 12 months post cessation of FI/MI. Eleven young people enrolled; median age 19 years, 8 female. Baseline median CD4 count 30 cells/μL (IQR 10-160), VL 12,870 c/mL. Outcomes at 12 months: 9/11 ever achieved VL < 50, 5 sustained undetectable VL, median CD4 140, mean CD4 gain 90 cells/μL at 1 year. Twelve months post cessation of MI/FI; six VL < 50, median CD4 75, mean CD4 gain 122 cells/μL. Total FI expenditure £1,350: £68 per 50 CD4 cells at 1 year, £55 at 24 months. To prevent death, adolescents with PaHIV require novel interventions to reverse poor patterns of adherence established since childhood. FI/MI improved virological and immunological outcomes with minimal expenditure. Extension of this pilot work for vulnerable individuals is now indicated.