Co-innovation is considered to be of great significance in addressing the lack of innovation capacity of a single entity. Under the influence of information technology, data assets are found to facilitate resource integration, achievement sharing, and collaborative innovation among enterprises within the supply chain. They are regarded as the core driving force for promoting co-innovation among enterprises. Based on empirical evidence from A-share listed companies in China between 2010 and 2022, the role of data assets in the channels and paths of co-innovation among upstream and downstream collaborators was explored. The results show that data assets exert a significant positive influence on firms’ co-innovation. The enhancement of firms’ total factor productivity, the advancement of human capital structure, and the alleviation of financing constraints are identified as key transmission mechanisms through which data assets contribute to firms’ co-innovation. The promotional effect of data assets on co-innovation is found to be more pronounced in large-scale, high-tech, and manufacturing enterprises. The findings confirm that data assets can enable enterprises to enhance co-innovation and offer both theoretical references and practical foundations for the country to develop new driving forces related to data elements and advance enterprise co-innovation.