Against the backdrop of the digital wave sweeping across the world, the digital application gap may lead to new wealth disparities. The digital application gap refers to the differences in regional participation and application capabilities in the digital society. The innovation cooperation of digital technology between regions is an important measure to narrow the digital application gap and promote common prosperity. This paper examines from the perspective of digital application gap whether collaborative innovation in digital technology research and development can promote common prosperity between regions in China by improving digital application capabilities. By manually collecting data on joint patent applications for digital technology in Chinese cities from 2013 to 2019, this paper investigates the impact of digital innovation cooperation on household income levels and interregional income disparities. The study shows that: First, digital innovation cooperation significantly improves household income levels, which is more effective for western regions. In regions with a high level of digital development, digital innovation cooperation has a greater impact on income enhancement, indicating that the digital development level has a supportive effect on the transformation of digital innovation cooperation results; the spillover effect of industry-university-research cooperation is significant, and its improvement effect on regional income is relatively stronger. Second, digital innovation cooperation promotes the growth of household income levels by enhancing digital application capabilities, and the improvement effect in central and western regions is greater than that in eastern regions. Third, the digital attention of micro-subjects positively regulates the improvement effect of digital innovation cooperation on regional digital application capabilities. This regulatory effect varies depending on the subject: Government attention tends to regulate digital development capabilities, while public digital attention tends to regulate digital wealth generation capabilities. Fourth, digital innovation cooperation has a shared spillover effect, which can bridge the digital application gap between regions, thereby narrowing the wealth gap and achieving shared development. This paper not only provides empirical evidence for the relationship between digital innovation cooperation and common prosperity, but also explores the internal mechanism of this relationship from the perspective of narrowing the digital application gap, providing policy inspiration for narrowing the digital application gap and achieving common prosperity.