Objective: This study aimed to investigate the development of young children’s metacognition and teaching abilities and the relationship between the two. Methods: Participants comprised 107 children aged 4 to 6 years, recruited through convenience sampling. Children’s metacognition and teaching abilities were assessed using a card game. Metacognitive knowledge was evaluated by examining their understanding of the difficulty levels of the game’s rules; monitoring ability was measured by assessing their self-evaluation of performance; and control ability was measured as their ability to identify rules that needed to be re-learned. Teaching abilities were subsequently assessed when the children taught a puppet to play the card game. Results: Analysis of variance (ANOVA) revealed that 6-year-olds demonstrated higher levels of metacognitive knowledge and monitoring than 4-year-olds, with control abilities improving significantly between ages 4 and 5 years of age. Older children demonstrated greater proficiency in teaching content and teaching strategies. Moreover, diverse relationships between metacognition and teaching abilities were observed, even after accounting for age and expressive vocabulary. Conclusions: These findings highlight early childhood as a critical period for the foundational development of metacognition. Teaching others provides valuable opportunities for children to exercise their metacognitive abilities.