This study aimed to explain ESP (English for Specific Purposes) students’ perception of AI Writing Tools to enhance their self-efficacy in writing skill by examining its impact on students’ learning experiences and perceptions. The present investigation employed a qualitative case study. The data collected by open-ended questionnaire in online form distributed to the 2^nd of ESP student in engineering programs of Malikussaleh University (UNIMAL) by using the purposive sampling technique. The data show that 78.5 % respondents use AIWTs frequently and 21.5% less frequently. Chat GPT was the most commonly used with 60.5% is chosen by student. Grammarly was the second most popular in this survey with 24.5%, quillbot with 6.5% still not familiar to student, and other AIWTs such as copy.ai, perplexcity.ai, and AI summarizer is chosen by respondent with 8.5%. The students felt that AI improved their motivation, offered interactive learning, decreased their anxiety, and provided easy for them to receive prompt feedback on their writing. These benefits allowed the students to concentrate on developing positive attitudes that would enable them to consistently improve their writing skills and succeed in all of their English writing tasks.