<p>Influencer marketing has underscored the importance of authenticity in attracting users. However, existing research often overlooks the identification and examination of influencer authenticity strategies. Based on signaling theory, this study focuses on the external signs to influencer strategic authenticity identified from online content: emotion, image, and brand disclosure. This study conducts an empirical test using a two-stage control function approach with field data from Weibo in China. The Bidirectional Encoder Representations from Transformers (BERT) model is employed to measure emotional valence and arousal, with results revealing their differential effects on digital engagement. Image count demonstrates an inverted U-shaped relationship with likes and comments. Brand disclosure negatively impacts reposts, but promotes likes and comments. Furthermore, it exerts a negative moderating effect on nonlinear relationship between images and comments. This study not only contributes to the literature on the authenticity strategies of social media influencers but also provides practical managerial insights for influencers, marketers, and social media platform administrators.</p>