Active engagement on social media platforms is crucial for firms to spread awareness of their brands and effectively interact with their customers. A firm's strategic orientation, especially innovation orientation and imitation orientation, may direct its efforts relating to its social media activeness (SMA). However, few studies have examined this phenomenon and the boundary conditions of strategic orientation influencing SMA. Our study draws upon strategic choice theory (SCT) to investigate how a firm's strategic orientations (e.g. innovation orientation and imitation orientation) influence SMA and how this effect is further moderated by CEO openness and environmental dynamism. Our study uses survey data from 203 firms in 2020 in combination with the firms' archival data from WeChat and Douyin in 2021 to test the proposed conceptual model. The results reveal that innovation orientation has a U-shaped relationship with SMA, which is weakened by environmental dynamism. Moreover, imitation orientation has an inverted U-shaped relationship with SMA, which is weakened by CEO openness but strengthened by environmental dynamism. These findings reveal the benefits and downsides of innovation orientation and imitation orientation, as well as the conditions that influence their effects on SMA.