<p>The present study was conducted to design, implement, and evaluate an educational program based on the Multi Theory Model (MTM) of health behaviour change to improve self-reported determinants of appropriate antibiotic prescribing among veterinary students. This mixed-methods study included qualitative interviews, questionnaire development and psychometric evaluation, a cross-sectional assessment, and a quasi-experimental intervention phase. In the intervention phase, veterinary students in the intervention and control groups completed an MTM-based questionnaire before and three months after the educational program. Descriptive statistics were reported as mean ± standard deviation, and the intervention effect in the two-group pre–post design was evaluated by comparing pre-post change scores between the intervention and control groups, corresponding to the group × time effect. Data analyses were conducted using SPSS version 22. Trial registration: IRCT20210911052432N1. There was a positive and significant relationship between MTM constructs and self-reported prescribing related behavioural outcomes among veterinary students. Significant group × time effects were observed for several MTM constructs, indicating more favourable changes over time in the intervention group than in the control group. The findings indicated that the MTM-based educational intervention improved self-reported determinants of appropriate antibiotic prescribing. These results suggest that MTM-based educational interventions may improve self-reported determinants of appropriate antibiotic prescribing among veterinary students and can inform future antimicrobial stewardship training programs.</p>