Despite the crucial role of uncertainty in entrepreneurship and management studies, the characteristics of uncertainty, its relationship with risk, and the sources of uncertainty affecting firms’ activities still require investigation. Extant literature lacks systematization, and concepts like risk and uncertainty are interchangeably used. The issue of uncertainty is present in very different fields of research but with different nuances and sometimes conflicting approaches. This work contextualises the concept of uncertainty in strategic management and entrepreneurship, because in both fields actors make decisions impacting on the survival and long run performance of their organisations. These decisions take place in a context shrouded in either high risk or uncertainty. We systematically analyse 96 papers and 28 books, and purposely integrate the economics, entrepreneurship, and organizational perspectives into our review. We contribute to extant knowledge by systematizing the literature about uncertainty. Firstly, we disentangle its construct from the construct of risk. Secondly, we reveal its complex nature, as a context at the interface between the external and the internal environment. Finally, we link this conceptualisation of uncertainty to the formation of opportunities in the processes of strategic management and entrepreneurship.