This study tested the effectiveness of a play-integrated preparatory programme to enhance a smooth transition for children from kindergarten to primary one. A randomized controlled trial was employed and 142 families were recruited. Children in the experimental group experienced greater happiness, fewer worries and lesser difficulty in psychological adjustment than children in the control group, providing evidence that the play-integrated preparatory programme is effective in enhancing a smooth transition for children. Findings from this study promote the awareness in parents and teachers that play is an important part of children's lives, which is essential for their normal growth and development.