Marketing Intelligence is a very attractive area for the application of sentiment analysis processes. Sentiment analysis can play an essential role in evaluating and optimizing influencer marketing in digital environments. Beyond the mere measurement of emotions, sentiment analysis can offer a deeper understanding of the impact of campaigns and influencers on audience perceptions. In this paper we present and discuss a sentiment analysis system conceived especially for identifying sentiments expressed in comments about influencers’ posts placed on social networks. This can contribute to a deeper understanding of the level of customer satisfaction, their engagement, and perceptions of the content and products being promoted, among other things. The system was applied to a set of diversified comments about influencers’ posts, which allowed for identifying the strengths and areas for improvement of each influencer.