Proactive environmental strategy (PES) is regarded as an effective tool to mitigate and root out the negative effects of an enterprise's development on the environment. Although institutional pressures have been viewed as major factors that can promote enterprises' PES, the results are still inconsistent. This mixed empirical result leads to a need to unpack the relationship between institutional pressures and PES, like the certain key mediating role of top managerial environment attitude. In addition, with the important role of new media in an enterprise's strategy, new media pressure plays a significant role in the PES field to induce enterprises to make a strategy change. Therefore, combining institutional theory and upper echelon theory, this paper explores the mediating roles of top managerial environment attitude between institutional pressures and PES, and the moderating roles of new media pressure, from a new media perspective. Our research model was tested by survey data from 345 top Chinese managers, and several results are established. First, the top managerial environment attitude significantly mediates the relationship between three institutional pressures and PES. Second, among the three institutional pressures, customer pressure is the most powerful one to influence the top managerial environment attitude toward PES. Third, new media pressure promotes and suppresses the positive effect between customer pressure, competitor pressure, and top managerial environment attitude. To promote the adoption of PES, it is important for top managers and governments to pay close attention to customer, regulatory, and competitor pressures, particularly when these pressures are amplified by new media.