While the sustainability transitions literature has highlighted the importance of agency in technological change, there is still limited understanding of the role of transnational actors, such as development agencies, which tend to be key drivers of energy transitions in low-income countries. This paper aims to fill this gap by investigating the role of transnational actors in the development of off-grid solar PV regime in Uganda, from the early 1980s to 2017. Specifically, we develop a typology of transnational actors and examine their roles in mobilizing the flow of knowledge, capital and technology towards shaping the country’s off-grid solar PV rural electrification regime. By discussing the pivotal role of foreign actors, their underlying motives and their shifting importance over time, the paper demonstrates empirically the highly transnational nature of regime development. In doing so, we contribute to the academic literature on actor-oriented determinants in sustainability transitions, as applied to low-income countries.