Higher education institutions are expanding the delivery of online and remote learning courses in the context of the COVID-19 pandemic. In turn, numerous challenges are foregrounded for those who are preparing and delivering these courses, including instructors, administrators, and teaching assistants. The purpose of our integrative review was to explore both the roles and responsibilities of teaching assistants in online, blended synchronous learning, and massive open online course modalities, as well as strategies for administrators and instructors to develop teaching assistants in these settings. A systematic search of databases and grey literature produced 1,603 texts; 42 were included for data analysis. We found that teaching assistant roles and responsibilities, as well as strategies to develop teaching assistants, are diverse and often poorly articulated. Roles and responsibilities were dependent upon the teaching assistant's previous pedagogical experiences and comfort level with non-traditional learning environments, institutional leadership, communication by the course instructor and the unique learning environment itself. Strategies to develop teaching assistants were often underdeveloped and influenced by resource constraints and institutional stances towards teaching assistant professional development programmes. Teaching assistant development across the three modalities primarily involved 'on-the-job' training, suggesting a need for further professional development interventions to be designed, delivered and evaluated. Results are synthesised and presented in pragmatic checklists to aid teaching assistants, instructors and administrators with planning and carrying out the three teaching modalities. Our results form the basis of an evidence-informed approach to assist institutions transitioning towards non-traditional learning environments.