Although some attention has been paid to entrepreneurial ethics, previous studies have mainly focused on the characteristics of entrepreneurs and new ventures when investigating the antecedents of new ventures’ ethical practices, ignoring the potential effects of entrepreneurs’ networking behaviors and entrepreneurial networks. This study investigated the effects of different types of entrepreneurs’ networking behaviors on new ventures’ ethical practices via the level of structural holes in entrepreneurial networks, and the moderating role of institutional support. According to survey data from 220 entrepreneurs, we found that network-broadening behavior had a J-shaped curvilinear relationship with the level of structural holes, while network-deepening behavior had a negative relationship with the level of structural holes. The structural hole level mediated the relationships between the two networking behaviors and ethical practices. Institutional support weakened the negative relationship between network-deepening behavior and ethical practice via the level of structural holes. This study enriches the understanding of the antecedents and mechanisms of new ventures’ ethical practice from the perspective of entrepreneurial network and provides practical suggestions for preventing unethical practices.