Informal institutions can play a crucial role in fostering corporate and policy innovation, especially when formal institutions are weak. However, their intangible nature makes them difficult to quantify. In this paper, we proxy the strength of kinship-based informal institutions using surname homogeneity among business owners, specifically, the extent to which they share a limited number of surnames within the same county. Our analysis reveals that a one-standard-deviation increase in the strength of informal institutions leads to a 21.1% increase in patent filings and an 18.9% increase in policy innovation. We find that kinship-related informal institutions foster corporate innovation by compensating for weak formal institutions, enhancing protection for intellectual property rights, facilitating access to finance, improving public service delivery, and promoting supply chain cooperation. We also suggest that kinship-related informal institutions encourage local governments to engage in policy experimentation, which relies on the collaboration of business owners. This experimentation process is easier to coordinate and monitor in counties dominated by a few kinship networks. Both informal institutions and policy innovation contribute to economic development and foster entrepreneurial market entries. However, the positive impact of informal institutions declines over time as formal institutions strengthen in China.