Vocabulary is one of the essential components of language learning because it enables young learners to understand and use English for communication. However, many young learners still experience difficulties in developing English vocabulary due to limited vocabulary knowledge and less engaging learning activities. Therefore, this study aimed to determine whether guessing games using flashcards affected young learners’ English vocabulary development. This study employed a quantitative approach using a pre-experimental one-group pre-test and post-test design. The participants were 14 kindergarten students aged 5–6 years old from Class B2 at TK Islam Alifah, Depok. The research instrument was a 25-item vocabulary test. The data were analysed using descriptive statistics, the Shapiro–Wilk normality test, and the Wilcoxon Signed-Rank Test with IBM SPSS Statistics. The findings showed that the students’ mean score increased from 71.08 in the pre-test to 91.71 in the post-test. The Wilcoxon Signed-Rank Test produced a significance value of 0.001, which was lower than 0.05, indicating a statistically significant difference between the pre-test and post-test vocabulary scores. Therefore, the null hypothesis (H₀) was rejected, and the alternative hypothesis (Hₐ) was accepted. The findings suggest that guessing games using flashcards supported young learners’ English vocabulary development by providing meaningful, enjoyable, and interactive learning experiences.