Background: Automobile technicians may experience occupational exposure to multiple heavy metals through routine workshop activities, but the relationship between biological exposure and clinical manifestations remains incompletely characterised in Nigeria. Aim: To compare clinical manifestations and biological markers of heavy-metal exposure among automobile technicians and non-occupationally exposed controls in Kano Metropolis, Northwestern Nigeria. Materials and Methods: This comparative cross-sectional study included 155 automobile technicians and 155 schoolteachers as the controls. We assessed clinical manifestations using interviewer-administered questionnaires and physical examination. Venous blood samples were analysed for ten heavy metals by atomic absorption spectrophotometry. We analysed data using descriptive statistics, chi-square or Fisher’s exact tests, independent-samples t-tests, and multivariate analysis. Results: Compared with controls, technicians had higher frequencies of general body pain (56.8% vs 12.9%), recurrent fever (69.0% vs 31.6%), catarrh (75.5% vs 51.6%), and diarrhoea (49.0% vs 30.3%) (all p≤0.001). Mee’s lines (18.7%) and skin hyperpigmentation (72.9%) occurred exclusively among technicians (p<0.001). Laboratory-confirmed heavy-metal exposure was substantially more common among technicians (81.9% vs 39.4%; OR=6.9, 95% CI: 4.1–11.6; p<0.001), with aluminium (69.7%), chromium (59.4%), and nickel (44.5%) most frequently elevated. However, none of the clinical manifestations remained significantly associated with occupational group after adjustment for confounders. Conclusion: Automobile technicians in Kano Metropolis demonstrated a substantially greater burden of clinical manifestations and biological evidence of heavy-metal exposure than the controls. The attenuation of clinical associations after adjustment highlights the multifactorial nature of these manifestations and supports the integration of biological monitoring with clinical assessment in occupational health surveillance.