High vaccination coverage plays an essential role in curbing epidemics and pandemics, making it important to have a country-specific valid and standardised instruments for assessing vaccination attitudes. This study aimed to assess the psychometric properties of the Motors of COVID-19 Vaccination Acceptance Scale (MoVac-COVID19S) in New Zealand. A total of 413 participants completed an online survey in June and July 2022, which included the MoVac-COVID19S questions, demographic factors, and a single-item measure of COVID-19 vaccination willingness. Confirmatory Factor Analysis (CFA) was used to examine the factor structures of the scale. Results indicated that the one-factor structure of the 9-item version best fitted the data compared to the one and four factor structures of the 12-item version, which showed acceptable fit indices after model modifications. All estimated fit indices were acceptable: CFI, GFI, and TLI > 0.95, RMSEA and SRMR < 0.08. The full scales of the MoVac-COVID19S demonstrated excellent reliability for both the 12-item (α = 0.91; ω = 0.91) and the 9-item (α = 0.94; ω = 0.95) versions. The bifactor model indicated a strong general factor, explaining 60–90% of the Explained Common Variance (ECV) for most items, surpassing specific factors. The MoVac-COVID19S is a reliable and valid scale to measure COVID-19 vaccination attitudes. The 9-item version appeared as the best choice for a unidimensional assessment. Future vaccination programmes can benefit from an adapted version of the MoVac-COVID19S to assess public attitudes towards new vaccines. Further psychometric assessment, including Rasch analysis, is recommended to strengthen the reliability and validity of the MoVac-COVID19S.