**Background:** Nigeria’s rapid urbanisation is accompanied by a distinct nutrition transition, characterised by a rising consumption of ultra-processed foods (UPFs). This shift poses a substantial threat to population health, necessitating a consolidated evidence base for policy formulation.

**Purpose and objectives:** This systematic review aimed to synthesise evidence from 2021 to 2026 on the scale of UPF consumption within urbanising Nigeria and to analyse its associations with obesity, type 2 diabetes, and cardiovascular disease risk factors.

**Methodology:** A systematic search of five electronic databases was conducted for peer-reviewed literature published between January 2021 and March 2026. Included studies quantitatively or qualitatively assessed UPF consumption and related health outcomes in Nigerian populations, with an urban focus. Data were extracted and synthesised narratively.

**Findings/Key insights:** Evidence confirms a consistent rise in UPF consumption, strongly linked to urban residence and younger demographics. UPFs are estimated to contribute 18–35% of total daily energy intake in major cities. This dietary shift is positively associated with an increased prevalence of abdominal obesity, hypertension, and dyslipidaemia, with associations often more pronounced in women.

**Conclusion:** The penetration of UPFs into the Nigerian diet, particularly in urban areas, is significant and growing. This trend is directly linked to adverse cardiometabolic health outcomes, representing an escalating key risk factor for non-communicable diseases.

**Recommendations:** Immediate public health strategies should include mandatory front-of-pack nutrition labelling, fiscal policies to disincentivise UPF consumption, and programmes to support affordable, traditional food systems. Further longitudinal and nationally representative research is required to strengthen causal inference.

**Key words:** Nutrition transition, ultra-processed foods, non-communicable diseases, urban health, Nigeria, dietary patterns.

**Contribution statement:** This review consolidates contemporary evidence on a critical public health issue, providing a coherent analysis to inform Nigerian health policy and intervention design.