This study investigates the competencies that should be addressed in early childhood mathematics education subjects for preservice early childhood teachers. Concerning this, the goal is to use the Delphi research method to derive the competency elements of preservice early childhood teachers’ early childhood mathematics education subjects. To that end, preceding domestic and international studies on competency were reviewed, and validity was determined by calculating the mean (M), standard deviation, content validity ratio, and data validity (agreement and convergence). Based on the opinions and analysis results of 15 Delphi experts, the content and composition of competencies were modified, integrated, and deleted. The competency factors of preservice early childhood teachers in the subject of early childhood mathematics were determined. Despite the importance of the early childhood education field and preservice early childhood teachers’ early childhood mathematics education competency, research on this topic is scarce, and the findings of this study are significant as basic research. Thus, it is expected that in the future, classes based on early childhood mathematics education competency will be added to college subjects for preservice early childhood teachers. Finally, based on the results of this study and its implications, this study investigates the competencies that should be addressed in preservice early childhood teachers’ early childhood mathematics education subjects which comprise 5 competency areas and 13 sub-elements: problem-solving, reasoning, creative convergence, communication, attitude, and practice suggestions were addressed.