An unhealthy diet is a major risk factor for chronic diseases. Although nutrition education and cooking demonstrations have resulted in favourable dietary changes, it is unclear whether this is sustainable for longer periods. This study aims to evaluate the long-term impact of a nutrition-led cooking intervention using the culinary education approach on dietary patterns based on My Healthy Plate (MHP). This was a quasi-experimental study involving patients who sought public primary care services in two polyclinics (mean age 59.3 years old). A self-administered survey was done at baseline, 6 months, and 1 year for both the intervention and the comparison groups. Participants in the intervention group were exposed to the health corner, which provided nutrition education and cooking demonstrations using the culinary education approach. A total of 216 participants completed the study at 1 year with a follow-up rate of 86%. Adjusted risk ratios (aRR) were obtained from negative binomial regression. Compared with the comparison group, participants in the intervention group were more likely to report adhering to the requirements of MHP at 6 months (aRR 1.83, 95% CI 1.12–2.99) and 1 year (aRR 1.54, 95% CI 1.10–2.16). Participants in the intervention group were less likely to add salt or sauces to food at 6 months (aRR 0.29, 95% CI 0.12–0.75) and 1 year (aRR 0.21, 95% CI 0.07–0.61) and more likely to remove fat when eating meat at 1 year (aRR 0.30, 95% CI 0.13–0.67) than the comparison group. The interventions at the health corner had a positive impact in helping patients achieve MHP recommendations, not adding salt and sauces to their food, and removing animal fat before eating. There is potential for expanding this initiative to improve healthy eating practices in other polyclinics.