Parents’ motivation to vaccinate their children against coronavirus disease 2019 (COVID-19) plays a crucial role in the uptake of COVID-19 vaccines among children. The Motors of COVID-19 Vaccination Acceptance Scale (MoVac-COVID19S) is a valuable tool for assessing individuals’ vaccination-related attitudes and the factors influencing their decision to be vaccinated against COVID-19. This study adapted the MoVac-COVID19S to create a parent version (P-MoVac-COVID19S) and examined the psychometric soundness of two P-MoVac-COVID19S versions (a 9-item version (P-MoVac-COVID19S-9) and a 12-item version (P-MoVac-COVID19S-12)) for assessing parents’ motivation to vaccinate their children. A total of 550 parents completed the P-MoVac-COVID19S and a questionnaire assessing the factors that impact parents’ intention to allow their children to receive the COVID-19 vaccine using a vaccine acceptance scale. We enquired about the level of parental worry regarding the adverse effects of COVID-19 vaccines on children’s health and the number of COVID-19 vaccine doses received by parents. The factor structures of the P-MoVac-COVID19S-9 and P-MoVac-COVID19S-12 were examined using confirmatory factor analysis. The internal consistency, test–retest reliability, and concurrent validity of the P-MoVac-COVID19S were also examined. The results revealed that the P-MoVac-COVID19S-12 has a four-factor structure, which aligns well with the theoretical framework of the cognitive model of empowerment; the P-MoVac-COVID19S-9 has a one-factor structure. Both the P-MoVac-COVID19S-9 and P-MoVac-COVID19S-12 had good internal consistency and test–retest reliability and acceptable concurrent validity. The results of this study demonstrated that the P-MoVac-COVID19S is a reliable and valid instrument for assessing parent’s motivation to vaccinate their children against COVID-19.