Innovation is the key driver for companies to maintain sustainable growth. In an open innovation environment, leveraging network relationships is an effective way to obtain the resources required by an enterprise to improve its innovation performance. However, existing studies have not reached a consensus on whether network relationships are favorable to innovation activities. This study aims to fill this gap using resource-based theory and social network theory. It examines the paths through which and the conditions under which vertical network relationships affect innovation performance. The empirical results show that: (1) vertical network relationships have a significant positive effect on innovation performance; (2) strategic flexibility positively regulates vertical network relationships and innovation performance; and (3) technological capabilities have a significant positive effect on innovation performance and play a mediating role between vertical network relationships and innovation performance. This study reveals the intrinsic mechanism whereby network relationships affect innovation performance and provides new ideas for how companies can improve their innovation performance and thus achieve sustainable development.