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Background Anaemia remains highly prevalent among females, primarily due to iron deficiency, which can be prevented through iron supplementation and by enhancing iron absorption using vitamin C. Guava, rich in vitamin C and other micronutrients, may serve as a natural adjunct to iron therapy. This systematic review and meta-analysis aimed to evaluate the effect of guava juice consumption on haemoglobin levels among females, including adolescent girls and pregnant women.Methods This review was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Randomised controlled trials (RCTs) and quasi-experimental studies published in English since 2000 were included. Literature searches were performed across PubMed, Scopus and Google Scholar. Two independent reviewers screened studies using EndNote X9, and data were extracted into Microsoft Excel. Study quality was assessed using the Cochrane Risk of Bias 2.0 tool for RCTs and ROBINS-I for non-randomised studies. Meta-analysis was conducted using Review Manager 5.4 and R Studio.Results 17 studies were included in the qualitative synthesis, and 12 in the quantitative analysis; 15 were quasi-experimental trials, and 2 were RCTs. Six studies involved adolescent females and 11 involved pregnant women. Most studies (n=9) evaluated guava juice in combination with iron supplementation. The pooled mean difference in haemoglobin was 1.71 g/dL (95% CI 1.37 to 2.05 g/dL, I²=89%), indicating a significant improvement post-intervention. Subgroup analysis showed mean differences of 1.52 g/dL (95% CI 1.09 to 1.95 g/dL, I²=66%) among adolescents and 1.84 g/dL (95% CI 1.37 to 2.32 g/dL, I²=93%) among pregnant women. In five studies comparing guava juice plus iron versus iron alone, the mean difference was 1.29 g/dL (95% CI 0.88 to 1.71 g/dL, I²=83%), favouring guava juice. The results of the sensitivity analysis were consistent with the main findings as well.Conclusion Guava juice consumption significantly improves haemoglobin levels among females and may serve as a cost-effective adjuvant to standard iron therapy. Further well-designed RCTs are warranted to validate these findings and guide public health recommendations.PROSPERO registration number CRD4202453529