Due to the advance in educational technology, several tools and applications have emerged for languages learning and teaching. Quizlet application is a language teaching and learning tool. It aims to help learners in language vocabulary acquisition. The present study aimed to examine the impact of using Quizlet application in English vocabulary acquisition of Omani deaf students in Al-Amal school, and their attitudes towards using the Quizlet Application to improve their vocabulary acquisition skills English language. It intended to determine whether the Quizlet application improve Omani deaf student's English vocabulary acquisition skills as a Foreign Language (EFL). The second objective is to examine the attitudes of the Omani deaf students toward Quizlet application as a learning environment. A quasi-experimental design was adopted to achieve the current research's objectives. The sample consisted of 20 students in the control group, and 22 students in the experimental group (total n= 42 students) who were enrolled in Al-Amal school for deaf students in Muscat governorate for academic year 2021\2022. The data collection instruments, which included a pre test and a post-test for the control and experimental groups, and an attitude scale for the experimental group, were validated and used to collect the required data.. The findings of the study revealed that there are no statistically significant differences between the experimental group and control group in the average of post-test scores. Although, the attitude questionnaire revealed that the students' attitude toward Quizlet was positive. Based on the findings, the study recommended the teacher should be incorporated more language skills in Quizlet to help deaf students to learn vocabulary faster and in an interesting way. This study is significant as it can contribute to the English Language Teaching (ELT) literature pertaining to the innovative and technological tools that can enhance deaf students' language skills in the 21st century. It is also important to English teachers and their deaf students in finding various ways of teaching and learning vocabulary in and outside classrooms.