This research explains the use of a chatbot to improve English writing skills, guided by Self-Determination Theory (SDT), focusing on three psychological needs: competence, autonomy, and relatedness. This research uses a qualitative case study method to explore in depth the learning process and student experiences. The participants in this study were 17 students from the English Education study programme at Walisongo State Islamic University. Data collection included reflective essays and semi-structured interviews. The findings reveal that chatbots significantly improve students’ competence by providing instant feedback on grammar, vocabulary, and sentence structure, boosting their confidence and understanding. Autonomy is enhanced as chatbots allow students to learn at their own pace and schedule, promoting self-regulated learning. Regarding relatedness, although chatbots lack human interaction, they provide a sense of companionship and facilitate discussions when students share chatbot outputs with peers. This study demonstrates that integrating chatbots into English learning can create a dynamic, personalized, and effective environment, addressing motivational needs as outlined in SDT. The findings are expected to provide valuable implications for educators and students who want to integrate technology into language teaching.