<![CDATA[Background: Non-communicable diseases (NCDs) constitute a major public health burden in Nigeria, where unhealthy dietary behaviour is a leading modifiable risk factor. Commercial drivers are a high-risk occupational group with limited access to structured health education. Aims: This study assessed the effect of a Theory of Planned Behaviour (TPB)-based intervention on unhealthy dietary behaviour among commercial drivers in Sabon-gari Local Government Area, Kaduna State, Nigeria. Methods: A pre-test post-test two-group quasi-experimental design was employed. Fifty commercial drivers were recruited from two motor parks using multistage sampling and randomly assigned to an experimental group (n = 25) and a control group (n = 25). The experimental group received six weekly one-hour TPB-based health education sessions delivered in Hausa; the control group received a cholera prevention placebo. A validated 14-item questionnaire (Cronbach's α: 0.784–0.893) measuring the four TPB constructs was administered at baseline and post-intervention. Data were analysed using Fisher's Exact Test and Mixed ANOVA (α = 0.05). Results: At baseline, both groups scored below the decision mean of 3.0 across all four TPB constructs. Post-intervention, the experimental group showed significant improvements in attitude (M = 4.39), subjective norms (M = 4.04), perceived behavioural control (M = 3.06), and behavioural intention (M = 4.00), all exceeding the decision mean. All Time × Condition interaction effects were statistically significant (p < 0.001) with substantial effect sizes (η² = 0.40–0.55). No significant improvements were observed in the control group. Conclusion culturally appropriate, Hausa-delivered TPB-based intervention significantly improved all four TPB constructs related to unhealthy dietary behaviour. Such theory-driven interventions should be integrated into workplace wellness programmes for commercial drivers. Key Words: Non-communicable diseases, Theory of planned behaviour, Unhealthy diet, Commercial drivers]]>
