Modified open-planning to define children’s spaces is important in preschool design. Cognitive school readiness (SR) is an objective of Malaysian preschools. This study investigates the correlation between modified open-plan spaces and cognitive SR in Malaysian preschools. A prospective cohort study involving 378 children at 18 Malaysian Ministry of Education (MOE) preschools was conducted. Compared to other preschool physical aspects (size, scale, circulation, facilities, indoor environment quality, safety, home bases, activity areas, and play yards), the quality of modified open-plan spaces showed the strongest correlation with children’s cognitive SR (Pearson’s r=0.658, p=0.000). Findings are hoped to promote better preschool designs.