The ESP Materials Development course is an online course designed to equip students with the knowledge and practical skills needed to design, develop, and evaluate materials for English for Specific Purposes (ESP). Students learn fundamental principles of ESP materials development and apply previously identified needs analysis results to formulate learning objectives, select and organize content, and develop instructional units that address learners’ specific needs. The course is implemented through Project-Based Learning (PjBL), in which students work collaboratively to develop an ESP materials project through a series of structured stages, including designing a materials template, organizing content, developing learning activities, selecting appropriate visual elements, and refining the final product. The course also covers the selection and use of digital and non-digital media and platforms to support effective, contextualized, and engaging ESP instruction. Through discussions, materials analysis, guided practice, and collaborative project development, students progressively produce ESP instructional materials that are systematic, communicative, visually appropriate, and relevant to the characteristics and needs of target learners. By the end of the course, students are expected to produce a complete and usable ESP materials product for a specific learning context. The course contributes to Sustainable Development Goal (SDG) 4: Quality Education by promoting the development of high-quality, inclusive, relevant, and learner-responsive instructional materials.