This study investigates the innovation behaviour of graduate start-ups at the individual level. It bridges the graduate enterprise literature and innovative entrepreneurship literature to put forward three arguments that ascertain why highly educated graduate entrepreneurs are not always innovative in starting new businesses. First, anchoring on the individual opportunity costs–entrepreneurial rewards nexus, it argues that graduate entrepreneurs will exploit opportunities innovatively if they expect the levels of entrepreneurial rewards that match their high human capital and high opportunity costs. Second, it is argued that entrepreneurial innovativeness is conditional on psychological factors such as students’ managerial self-efficacy and overconfidence. Third, it is also argued that the nonlinear relationship between entrepreneurial innovativeness and entrepreneurial rewards will drive graduate entrepreneurs to exploit even riskier opportunities in search for high rewards. This study operationalizes the theoretical framework with an empirical model and estimates it using a graduate entrepreneur sample from a questionnaire survey in China. Our results suggest that innovation behaviour of graduate start-ups is influenced by the quantity of human capital, psychological make-up and expectations of entrepreneurial rewards.