Driven by the initiative of e-learning, mobile technologies such as tablets, with the merits of portability and accessibility, have become vital tools for creating ubiquitous learning and mobile learning (m-learning) environments in science education. The reconstruction of the science learning environment enabled by mobile technologies may influence students' learning engagement and correspondingly affect their science learning performance. Considering the limited empirical studies on student engagement in the m-learning environment at the senior secondary level, this study focuses on exploring the characteristics of students' engagement in a mobile technology-supported science learning environment. In the study, a class with 45 10th grade students and three teachers at a senior secondary school was videotaped and observed. The data of students' behavioral, emotional, and cognitive engagements from 60 science lessons was coded and analyzed qualitatively and quantitatively from the social-cultural perspective. On that basis, the correlations among these three dimensions of engagements in m-science learning environment were further calculated. The findings indicated the progress and pitfalls of current mobile technology-supported teaching and learning practices in science education. The results and discussions will inform the pedagogical design and implementation of mobile learning in science education.