Unlike elementary and secondary education, early childhood education lacks approved textbooks, making teachers’ instructional activity design a key factor affecting educational quality. However, instructional activity design is a highly knowledge-intensive, dynamic, and complex task that requires professional support for pre-service preschool educators. Based on concerns about early childhood education quality and pre-service preschool educators’ needs in instructional activity design, this study aims to develop a rubric aligned with the concepts of the Early Childhood Education and Care Curriculum Framework to assist pre-service preschool educators in developing their instructional activity design capabilities. The study employed a two-phase approach. The researchers first applied the Delphi technique to construct 20 evaluation indicators across four dimensions: instructional objectives, content, methods, and assessment. The rubric was subsequently validated through expert review to establish content and expert validity. The rubric was then applied to evaluate instructional activity designs created by sophomores, juniors, and seniors in teacher preparation programs, confirming its reliability and discriminant validity. Analysis across the three grade levels revealed that pre-service educators demonstrated stronger competencies in designing teaching content and preparing teaching materials but exhibited challenges in areas such as implementing learning assessment, analyzing children’s prior experiences, and planning appropriate questioning, guidance, or scaffolding strategies. These findings provide valuable insights into pre-service preschool educators’ learning needs in instructional activity design. The developed rubric serves dual purposes: as both an assessment and guidance tool for teacher educators, and as a self-learning and self-assessment instrument for pre-service preschool educators. The results offer teacher educators empirical evidence to inform their instructional approaches in supporting the development of instructional activity design competencies among pre-service preschool educators.