Starting early in life, children, especially girls, experience obstacles when it comes to developing an interest in STEM. Although early childhood (EC) educators face an important task in promoting girls (and boys) in STEM, they often face challenges in doing so. Therefore, it is crucial for EC educators to cultivate positive attitudes, self-concepts, and STEM skills. To address these identified issues, a three-month professional development program was created for EC educators. This professional development program was evaluated using a pre–post design with a focus on the self-concept and gender stereotypes of EC educators. The program involved 30 female EC educators in evaluating these aspects. The statistical analyses show positive results in enhancing educators’ self-concepts and reducing gender stereotypes over the course of this professional development program. The results suggest the potential of the blended learning design in this professional development program and indicate that this program could serve as a promising model for future interventions.