Generative AI is a type of artificial intelligence (AI) that can significantly enhance English vocabulary. This study employed a mixed methods approach (Concurrent Nested Design) to examine the effectiveness of AI-Generative Tools in improving the vocabulary and engagement of Omani 4th-grade students in the English Subject. Data was collected using three instruments: (1) an English achievement test (Pre-Posttest), (2) an observation checklist, (3) and a semi-structured Interview. The Pre-Posttest was used to measure the impact of using the Curipod tool on the students' English Vocabulary. The test consisted of 10 questions to assess the students’ English Vocabulary. The content validity of the pre-posttest was determined, and the reliability of the test was measured before using it. The study involved a sample of 62 fourthgrade students from Al-Abrar School for Basic Education (grades 1-4). These students were divided into two groups for the experiment: An experimental group of 30 students and a control group of 32 students. Moreover, an observation checklist and semi-structured interviews were utilized to assess students' engagement in learning English vocabulary through the Curipod tool in the classroom. The validity and reliability of both tools were assessed through measures aligned with the criteria for qualitative research, specifically credibility criteria (Member check and Peer briefing). The observation checklist consisted of preexisting themes and indicators that were derived from previous studies. It was utilized to observe 62 students across both experimental and control groups. Similarly, the semi-structured interviews consisted of three questions administered to two teachers from experimental and control groups. Quantitative data collected from this study were analyzed using the Statistical Package for the Social Sciences (SPSS) software and independent sample t-test. Additionally, qualitative data obtained through an observation checklist and semi-structured interviews were analyzed using a thematic analysis approach. The findings revealed that students exposed to the Curipod tool showed significantly greater improvement in their English vocabulary in both pre and post-tests than those who did not use the tool. In addition, high levels of engagement were observed among students using the Curipod tool, as evidenced by the observation checklist and semi-structured interviews. Based on the findings, the study recommended that Educators and policymakers integrate AI-driven tools like Curipod into Oman's English education to enhance vocabulary and academic performance. Teachers need training to use these technologies effectively, and curriculum developers should incorporate them into education.