In the dynamic environment, top managers comprehensively scan, capture, and evaluate the internal and external environment to stimulate cross-boundary innovation. In this process, how executive alertness towards resources and opportunities plays a role deserves exploration. Based on the “awareness-motivation-capability (AMC)” framework of dynamic competition theory, the relationship between executive alertness and cross-boundary innovation is examined, as well as the moderating effect of performance shortfalls and dynamic capability. Using the data of listed companies from 2012 to 2023 in Shanghai and Shenzhen Stock Exchanges, the results indicate that both resource alertness and opportunity alertness have a positive effect on cross-boundary innovation. Furthermore, performance shortfalls and dynamic capability strengthen the relationship between executive alertness and cross-boundary innovation. The heterogeneity test result shows that there are systematic differences in the driving effect of executive alertness on cross-boundary innovation among enterprises of different technological attributes and property rights. The research results expand the research on the antecedents of cross-boundary innovation, and provide practical inspiration for cross-boundary innovation.