This study proposes a future model of an online textbook for Korean Language Arts by reflecting future changes in education and the characteristics of the Korean Language Arts subject. The textbook was conceptualized as a system that supports and manages teaching and learning through the Internet as well as individuality, variability, interactivity, and expandability were presented as the textbook’s main characteristics. The main principles to be considered while developing the textbook were listed as a textbook consistent with the development of Korean Language Arts competence, a textbook that supports individualized education, supports growth through evaluation, and that promotes the connection and expansion of language and culture. Based on these discussions, the textbook model’s core components were proposed as the operating system and basic software, developed materials, support and management of teaching and learning, and external links. In the final part, the need for reexamining the textbook’s legal definition, the search for practical support measures for future textbooks, the development of a textbook quality management system, and the study of teaching, and learning and evaluation methods were discussed. The latter will be used for future textbook development to spread future online Korean Language Arts textbooks.