People living with HIV (PLHIV) have a 20-fold risk of tuberculosis (TB) disease compared to HIV-negative people. In 2021, the uptake of TB preventive treatment among the children and adolescents living with HIV at the Baylor-Uganda HIV clinic was 45%, which was below the national target of 90%. Minimal evidence documents the enablers and barriers to TB preventive treatment (TPT) initiation and completion among children and adolescents living with HIV(CALHIV). We explored the facilitators and barriers to TPT initiation and completion among CALHIV among adolescents aged 10-19years and caretakers of children below 18years. We conducted a qualitative study from February 2022 to March 2023, at three paediatric and adolescent HIV treatment centers in Uganda. In-depth interviews were conducted at TPT initiation and after completion for purposively selected health workers, adolescents aged 10-19 years living with HIV, and caretakers of children aged below 18years. The desire to avoid TB disease, previous TB treatment, encouragement from family members, and ministry of health policies emerged as key facilitators for the children and adolescents to initiate TPT. Barriers to TPT initiation included; TB and HIV-related stigma, busy carer and adolescent work schedules, reduced social support from parents and family, history of drug side effects, high pill burden and fatigue, and perception of not being ill. TPT completion was enabled by combined TPT and ART refill visits, delivery of ART and TPT within the community, and continuous education and counseling from health workers. Reported barriers to TPT completion included TB and HIV-related stigma, long waiting time. Non-disclosure of HIV status by caretakers to CALHIV and fear of side effects was cited by health workers as a barrier to starting TPT. Facilitators of TPT initiation and completion reported by healthcare workers included patient and caretaker health education, counselling about benefits of TPT and risk of TB disease, having same appointment for TPT and ART refill to reduce patient waiting time, adolescent-friendly services, and appointment reminder phone calls. The facilitators and barriers of TPT initiation and completion among CALHIV span from individual, to health system and structural factors. Health education about benefits of TPT and risk of TB, social support, adolescent-friendly services, and joint appointments for TPT and ART refill are major facilitators of TPT initiation and completion among CALHIV in Uganda.