The formation strategy of entrepreneurial teams significantly impacts their ability to navigate venture challenges. Existing research suggests that both an interpersonal-attraction strategy (relying on relationships with similar others in a close network) and a resource-complementary strategy (instrumental emphasis on complementary expertise and resources) can enhance entrepreneurial performance. However, our understanding of interplay and the jointly implications of these two strategies remains quite limited. Taking a dynamic ambidexterity perspective, this study examines the influence of dual formation strategy on entrepreneurial team’s effectiveness through the development trajectory of team ambidexterity. Based on a longitudinal study involving a sample of 912 members from 228 teams who participated a business simulation game contest, we found that entrepreneurial teams that adopt a dual formation strategy can exhibit a more positive team ambidexterity trajectory, leading to higher team effectiveness compared to teams using only interpersonal attraction or resource complementarity strategy. These findings provide several theoretical and practical implications and also suggest some directions for future research.