The present study aimed to investigate the mediating role of children's working memory levels in the relationship between attachment insecurity levels and emotion regulation skills. A total of 150 children aged 5 years, 75 girls and 75 boys, were selected by the stratified cluster sampling method and their mothers participated in the study. The data were collected using the Memory Battery for Preschool Children, Attachment Insecurity Screening Inventory, Emotion Regulation Skills Scale and Coping with Child's Negative Emotions Scale. The findings indicate that the child's level of attachment insecurity to parents is directly associated with both emotion regulation skills and working memory capacity. Additionally, the study reveals that as the working memory levels of children increase, their emotion regulation skills also increase. The final finding of the study indicates that the child's working memory levels mediate the effect of attachment insecurity on emotion regulation skills. The results of this study indicate that children with insecure attachment should be given support to improve their working memory performance, to enhance their emotional regulation skills. This suggests that even in the context of attachment insecurity, the development of emotion regulation skills can be supported by fostering working memory development.