Abstarct: This study investigated the impact of gamification strategy on English vocabulary development among fourth preparatory students in Iraq. Using a quasi-experimental design, a sample of 82 students from Al-Jadaa Mixed Private Secondary School in Mosul was randomly divided into control and experimental groups. The experimental group was taught using a gamification strategy incorporating digital platforms (Kahoot! Quizizz, Quizlet, and Wordwall), while the control group received traditional instruction. A validated and reliable researcher-developed vocabulary test was administered as pre- and post-assessment. Data were analyzed using independent samples t-tests, effect size, and Eta square. Results revealed statistically significant improvements in vocabulary scores for the experimental group, with a large effect size (η² = 0.39), indicating that gamification positively and substantially enhances vocabulary acquisition. baxsed on these findings, the study recommends that curriculum designers integrate gamified activities into English textbooks and that teachers and supervisors receive training in implementing gamification strategies.