This research aims to develop an Android-based e-textbook for a learning media course to enhance student learning outcomes. The learning media course was selected because students require an e-textbook to improve their comprehension of the criteria and creation techniques of learning media during online learning. This study utilized the research and development method with the 4D model created by Thiagarajan and Semmels. Six learning media expert validators tested the product’s feasibility, and the product’s effectiveness was tested on students through experiment research. Descriptive statistics and an eligibility criteria table were used to determine the product’s feasibility and usability. In addition, an independent sample t-test was used to determine the product’s effectiveness. According to the expert evaluation results, the product validity falls into the "very good" category (4.50 out of 5, or 90%) in aspects of language, presentation, appearance, and usefulness. The effectiveness test results indicated that the Android-based e-textbook significantly affects student learning outcomes. In addition, students’ perceptions of the usefulness, ease of use, and satisfaction of the Android-based e-textbook are also in the "very good" category (4.27 out of 5, or 85%). According to a qualitative data survey, students mentioned that the most useful aspects of the product were the tutorial videos, quizzes, menus, and page markers. Nevertheless, a few students experienced difficulties with their internet connection and reading limitations.