Due to the tumultuous COVID-19 pandemic, the use of advanced technology in language education is currently on the rise, with English education being no exception. Simultaneously, the advancement and expansion of technology provide English as a foreign language students with multiple channels and opportunities to reinforce the four skills of English (reading, writing, speaking, and listening) to varying degrees both inside and outside the classroom. While previous studies have highlighted the feasibility and sustainability of blended learning in facilitating English skills, few studies have investigated the impact of mobile blended active language learning (MBALL) on promoting the English critical reading skills of Thai high school students. In hopes of filling this gap, the present study used both quantitative and qualitative methodologies to investigate the effects of MBALL on improving Thai high school students' English critical reading skills and their opinions on the use of MBALL. Pre- and post-tests were used to compare the students' critical reading scores before and after the MBALL implementation. A questionnaire was used to determine the students' opinions on the use of MBALL, and individual semi-structured interviews were employed to obtain more-detailed information. The results of the tests revealed that the Thai high school students' English critical reading skills had improved after implementation of the MBALL curriculum. Furthermore, the findings of the questionnaire and interviews suggested that the Thai high school students were enthusiastic about the use of MBALL.