Childhood obesity is a prevalent, multifactorial condition that increases morbidity and chronic disease risk into adulthood, yet its management remains a challenge for health professionals. Growing recognition of inter-individual metabolic variability has increased interest in personalised and precision nutrition (PPN), which uses individual-level data to tailor dietary care and may improve obesity management outcomes. Existing reviews focus on randomised controlled trials and anthropometric outcomes, with little attention to contextual factors, acceptability, feasibility and experience. This review aimed to synthesise the evidence base more broadly to examine both the effectiveness and care-related experience of PPN interventions for paediatric obesity. The mixed-methods systematic review was conducted in accordance with Joanna Briggs Institute methodology(1) and PRISMA 2020 guidelines(2). Six databases were searched for eligible studies published in English from 2000 to March 2026, involving youth aged 5–18 years with overweight or obesity receiving a PPN-informed dietary intervention. PPN level was assessed based on a four-level personalisation framework(3). Data were synthesised using a convergent-segregated approach. Overall, 46 unique studies were included in this review: 42 quantitative and four mixed-methods. PPN was determined to be low-level (level 1) in 15 studies (32.6%), moderate-level (level 2) in 27 studies (58.7%) and high-level PPN (level 3) in four studies (8.7%); no studies used very high-level PPN (level 4) such as omics-informed tailoring, advanced microbiome profiling or integrated systems modelling. 22 of 34 (64.7%) studies reporting experience outcomes described dietitian or nutritionist involvement. Clinically significant BMI z-score reductions (≥ 0.2 units) were reported in 20 of 34 studies (58.8%). Eight of 16 multi-arm studies (50.0%) achieved clinically significant reductions; five showed significant between-group differences favouring PPN, with three also meeting the clinical threshold. Greater personalisation did not correspond with effectiveness: of the 20 studies with clinically significant reductions, seven (35.0%) used low-, 11 (55.0%) moderate- and two (10.0%) high-level PPN. Clinically significant reductions were more common in longer interventions which incorporated repeated contact, structured follow-up or active self-monitoring. Younger populations were more common among studies with clinically significant reductions (75.0% vs 57.1%), while sample size and digital or mHealth use were similar between groups. Experience, acceptability and/or implementation outcomes were reported in 34 of 46 studies, but only 13 studies directly assessed participant, caregiver or health professional experience. Overall, PPN interventions were acceptable to youth and their carers and were generally associated with clinically significant reductions in BMI z-score in youth with overweight and obesity. PPN has the potential to enhance paediatric obesity management by improving patient experience, engagement with interventions, and consequently, health outcomes for young people living with overweight and obesity. Future PPN research should consider using a more consistent definition of PPN, as well as collecting data on care-related experiences of PPN alongside effectiveness outcomes.