The disruption that is happening in the world of education at this time is triggered by technological developments in the era of digital transformation or commonly known as the industrial revolution era 4.0. where it takes a concept and a learning process mechanism that integrates technology with education. The use of technology, both hardware and software, has begun to be widely applied in the field of education, one of which is as a learning medium. The research conducted is Research and Development (R and D) research with 4D development procedures (Define, Design, Develop, Desseminate). The development carried out aims to develop learning media in the form of a smartphone application for mobile learning the Operating System course at STKIP Muhammadiyah Muara Bungo. The data analysis technique used descriptive analysis techniques to describe the validity, practicality, and effectiveness of the developed learning media. The results obtained from this development research: (1) the validity of the smartphone application for mobile learning is declared valid in the media and material aspects, (2) the practicality of the smartphone application for mobile learning based on direct observation, the responses of lecturers, and students are stated to be very practical, (3 ) the effectiveness of smartphone applications for mobile learning is stated to be effective in improving learning outcomes. Based on the findings of this study, it was concluded that the smartphone application for mobile learning was declared valid, practical, and effective to be used as a Learning Media in the Operational System course.