There is an increasing trend in adopting English-medium instruction (EMI) as an academic lingua franca in response to higher education internationalization. Considered as an innovation in content teaching, its adoption rate at Indonesian higher education remains questionable. Using the Diffusion of Innovation (DOI) frameworks, this paper aims to explore the EMI attributes regarding its relative advantage, compatibility, complexity, trialability, and observability and to examine the relationships between the EMI perceived attributes and the attitudes and behavioral intention towards EMI among university students in the Indonesian context. This study is a mixed-method study. The quantitative data were collected using Likert-scale questionnaires from 125 students from two reputable universities, while the qualitative data were obtained through focus-group discussions. The quantitative data were statistically analyzed using SmartPLS to address the research problems. Thematic analysis was employed for the qualitative data for explaining and clarifying the quantitative findings. The findings show that EMI is considered very highly advantageous and compatible, highly observable and trialable, and surprisingly low in complexity to learn content courses. In addition, the EMI perceived relative advantages and compatibility that were predictive to the students’ attitudes toward EMI. Finally, perceived relative advantages, trialability, and observability of EMI were predictive to the students’ behavioral intention to enroll in EMI. EMI is therefore worth applying at higher education institutions in Indonesia as an approach to enhance both students’ content understanding and English competence and to support Indonesian universities’ internationalization vision.