Drawing on elements of self-determined learning or heutagogy, the graduate employability impact of the UK's leading Universities Business Challenge (UBC) competition is investigated over a five year period of from 2012-17. A central research question was addressed, namely: "what do inter-university business simulations, such as the UBC, contribute to developing self-determined learner skills and graduate employability?" A mixed-methods research approach combined structured equation modelling (SEM) results of 2 student surveys from over 50 (UK) universities, with qualitative analysis of 7 student focus-groups and 15 semi-structured interviews. The article contributes to new knowledge about the role of UBC as an example of an inter-university business simulation. It models the direct and indirect effects of personal/managerial skills development and reflective learning capacity (as mediator) on perceived employability impact. There is fresh evidence to support the claim that "reflective learning" is important in the study of self-determined learning and graduate employability.