This study aims to analyze the interest in learning Indonesian among sixth-grade students at AnubanJitjongrak School in Krabi, Thailand, where the language was introduced through non-formal instruction outside of regular class hours. The study was motivated by the fact that Indonesian is not taught as a formal subject at the school; consequently, language exposure occurred through daily interactions, language games, and simple conversations during community service and international internship activities. A qualitative descriptive approach using a case study method was employed. Data were collected via a three-point Likert scale questionnaire comprising ten questions administered to the sixth-grade students. The data were analyzed descriptively to characterize the students’ responses and their interest in learning Indonesian. The results indicate that the students demonstrated a positive interest in learning Indonesian, despite the language not being part of the formal curriculum. The majority of students showed interest, attentiveness, and active participation—such as paying attention to vocabulary introductions, asking about word meanings, and attempting to pronounce Indonesian words. Furthermore, learning through games and casual conversation helped boost the students’ intrinsic motivation and fostered a more comfortable learning atmosphere. It can be concluded that introducing Indonesian outside of formal class hours positively contributed to cultivating the sixth-grade students’ interest in learning the language, suggesting that a non-formal approach holds potential as an effective alternative strategy for introducing Indonesian to foreign learners at the primary school level.