Combining organizational learning theory and institutional theory, this study examines how managerial learning affects the new product innovativeness of high-tech firms in an emerging market and assesses whether such an effect is conditional on institutional support. We propose that managerial learning helps firms increase the innovativeness of their new products, but this effect declines at high levels of managerial learning. Furthermore, we suggest that institutional support at government and individual levels enhances the effect of managerial learning on new product innovativeness while organization-level institutional support reduces the effect. Empirical findings based on a survey of 174 high-tech firms in China support most of the hypotheses. This study sheds light on the driving forces of new product innovativeness for firms in an underdeveloped institutional environment.