This semi-quasi-experimental study aimed to identify the effects of narrating picture books in promoting vocabulary learning and retention in preschoolers in the English as the second language (ESL) setting. The research has conducted in an English medium preschool in Shizuoka prefecture, Japan. The researcher used twenty children aged 4-6 years old, ten as the experimental group and ten as the control group. Three picture books; Peanut Butter and Jelly: A Play Rhyme by Nadine Bernard Westcott, The Berenstain Bears and the Spooky Old Tree by Stan and Jan Berenstain, and Just Grandma and Me by Mercer Mater, were carefully selected to narrate during the intervention. A total of 15 sessions were taken to complete the study. During the intervention, flashcards were used to highlight the five focused vocabulary of Peanut Butter and Jelly. In The Berenstain Bears and the Spooky Old Tree, five repeatedly appeared words were chosen for the evaluation process. Five words of Just Grandma and Me were neither repeated nor flashcards have been used, thus regular story narration. Pre, post, and delayed post-tests were executed to collect data. The results show that narrating storybooks significantly impacts vocabulary learning and retention. Further, the use of flashcards focusing on the story's keywords helps children retain vocabulary more than repetition and just narrating.