Background: Vitamin D deficiency (VDD) is a serious public health issue, particularly among women, due to a lack of knowledge regarding the importance of Vitamin D (VD) and the method of preventing its deficiency. The research aimed to investigate the effect of adopting health belief model to improve female employees' knowledge, beliefs, and preventive behaviors regarding vitamin D deficiency. Method: A structured educational intervention based on HBM was implemented using a quasi-experimental study among 300 female employees from 14 faculties affiliated to Mansoura University in Egypt using stratified sampling with a proportional allocation technique. Tools: A self-administered structured questionnaire consisting of five parts was used for data collection before and three months after the intervention. The intervention involved group education, counseling, and follow-up. Results: There were statistically significant differences in mean scores of total knowledge, VDD-preventive behaviors, and HBM constructs before and three months after the intervention with P≤0.001. Three months following the intervention, there was a statistically significant positive connection with (p≤ 0.001) between total knowledge, total VDD-preventive behavior, and HBM constructs scores. Also, there were statistically significant differences between participants' knowledge scores regarding VD and VDD with employees' age, occupation, and years of experience in the pre and post-test with p ≤0.001. As well, there were statistically significant differences between participants' VDD-preventive behaviors with their occupation and level of education in the pre- and post-test with p≤0.001 and p=0.006 respectively. Moreover, there were statistically significant differences between participants' health belief scores with their age, working place, occupation, income, years of experience, medical and medications history in the pre- and post-test p<0.05. Conclusions: Implementing educational intervention based on HBM improves the female employees' knowledge regarding VD and VDD, contributes to the advancement in all constructs of the health belief model, and positively affects their VDD-preventive behaviors. Recommendations: Health Belief Model constructs should be an essential part of the existing VDD management program. More research is needed to continue investigating the effectiveness of HBM for a longer period of follow-up time after the intervention.