In this systematic review, we scrutinise adolescent nutrition in Nigeria, focusing on dietary patterns, intake, and nutritional status. Through a systematic examination of observational studies across three major databases, we analysed data from 67,844 adolescents. Our exploration revealed 102 studies, predominantly cross-sectional, addressing various nutritional dimensions. However, only 13% of these studies demonstrated low risk of bias, with none offering national representation and most concentrated in specific, school-based regions. The findings underscore a complex nutritional landscape with widespread malnutrition and highlight the critical need for high-quality, comprehensive data. The dominance of cross-sectional designs and regional biases in existing research calls for cautious interpretation and suggests a pressing need for more robust, nationally representative studies to guide future nutritional interventions and policy-making in Nigeria.