This paper evaluates the effectiveness of an educational intervention based on the transtheoretical model aimed at increasing physical activity (PA) participation among female employees in Bandar Abbas city (Iran) healthcare centers in December 2017 and August 2018. Using a semi-experimental interventional study design with a randomized and multi-stage method, 100 participants were included in both the intervention (n = 50) and control groups (n = 50). Data collection involved questionnaires assessing demographic information (age, gender, marital status and education), stages of change in PA behavior, Perceived Benefits, Barriers and Self-efficacy. The data were analyzed using SPSS-16, employing both descriptive (mean, SD, frequency, percentage) and inferential statistics (t-tests, chi-squared tests, etc.). Prior to the educational intervention, 19 participants (0.38%) in the intervention group engaged consistently in PA (stages 4–5). After 3 and 6 months of intervention, these numbers increased to 29 (0.58%) and 25 (0.50%), respectively. This improvement was statistically significant compared to the pre-intervention stage (P < 0.001). The findings highlight the importance of theory-based behavior change models and health education programs in promoting PA and combating sedentary lifestyles. Although focused on a specific population in Bandar Abbas, the intervention can serve as a model for similar programs targeting diverse social classes and populations.