The aim of the study was to examine assistive technology (AT) use, elements teachers take into consideration when selecting AT, and barriers from the standpoint of teachers of students with severe intellectual and developmental disabilities. To answer the research questions, the researcher employed a sequential explanatory mixed-methods design. A self-administered online survey and interviews were conducted to collect data. A total of 92 special education teachers from four special education institutes were surveyed, and five teachers were interviewed to provide interpretations for the analysed quantitative data. Results demonstrated there were cultural factors that could influence AT use with students. Findings revealed there was a lack of AT use, with teachers reporting higher use of low-tech than mid-tech and high-tech. The most reported barriers were lack of AT devices and lack of training. The results also revealed there were statistical differences in AT use between the four special education institutes and between teachers with previous AT training. Four major themes and several sub-themes emerged from the interviews. The themes were (a) AT use, (b) considerations, (c) barriers, and (d) professional development. These themes made it possible to interpret and elaborate on the quantitative data. The findings suggest the necessity of professional development for teachers, an increase in financial support, and provision of appropriate curriculum for successfully using AT in classrooms.