The opening of government in a number of countries has implications for innovation processes and the potential for inclusive development outcomes. After unpacking some of the key thinking around openness proffered by Karl Popper and others, we explore the adoption of open government practices in innovation by considering four important instruments: the opening of innovation and technology policy processes, co-creation and collaborative solution development by civil servants, government entities acting as innovation brokers, and public sector procurement of innovation. Through a case study of South Africa, we highlight how innovation actors prioritise particular values of openness over others. For example, in pushing for more open interaction between state and non-state actors as a more effective way of addressing social challenges, values of legality and impartiality are often minimised. This oversight leads to project failures, legitimacy crises and exploitation of relationships by powerful entities. In response, we suggest that public sector innovation programmes and platforms can more explicitly recognise different values, especially from emergent grassroots innovation networks, and thereby enable sustainable application of open government practices.