Recent research has pointed out the emergence of new online actors, especially in the domain of fashion and lifestyle—“social media influencers” or SMIs (Etter, Colleoni, Illia, Meggiorin, & D’Eugenio, forthcoming). SMIs are defined as “people who possess greater than average potential to influence others due to such attributes as frequency of communication, personal persuasiveness or size of—and centrality to—a social network.” As SMIs become professionals, with a mass audience of followers, they gain competence in generating sophisticated content such as creation of stories, videos, visuals, etc. (McQuarrie, Miller, & Phillips, 2013). As such, SMIs are tempted to leverage their online influence to partner with brands. One of the reasons brands collaborate with SMIs is that they are considered trustworthy and “one of the few forms of real, authentic communication” (Scott, 2015, p. 295). Authenticity is recognized in the marketing literature as an important attribute, as consumers increasingly desire authenticity in their products and brands (Chronis & Hampton, 2008). A notion of authenticity which has been gaining acceptance revolves around whether an individual or brand expresses their true self (Moulard, Raggio, & Folse, 2016). Holt (2002, p. 83) notes, “To be authentic, brands must be disinterested; they must be perceived as invented and disseminated by parties without an instrumental economic agenda, by people who are intrinsically motivated by their inherent value”. However, collaborating with brands may question SMIs authenticity as their inner desires to focus on products they are passionate about are challenged by commercial opportunities to showcase brands that they would not ordinary like. Their credibility might be questioned as the persuasive effect of their messages is often attributed to their perceived noncommercial nature as compared to branded advertisements. Despite growing research on influencers and acknowledged pressure of pursuing financial gains (Abidin & Ots, 2015), past research has overlooked the challenges to remain authentic when collaborating with brands. As such, our research focuses on the question: what are the strategies of SMIs to maintain authenticity while they are under commercial pressure? To answer it, we conducted a research in the context of fashion, beauty and lifestyle, as it is one of the most successful and visible domains of digital production. We analyze posts from 49 influencers participating in 9 brand campaigns that employed multiple SMIs simultaneously. These observations are complemented with 27 interviews with SMIs to understand “behind the scene” goals pursued to project this authenticity. Results suggest that SMIs implement two potentially complementary strategies expressing authenticity under commercial pressure: 1) passionate authenticity, which refers to one’s expressing of his/her inner self and being passionate even when involved in a collaboration, and 2) informational authenticity, which refers to being consistent with the facts and not lying about the partnership, the influencer or the products promoted. From a theoretical standpoint, the notion of passionate authenticity has been established in the previous literature (Moulard, et al., 2016), but we identify a new form of authenticity that we name informational authenticity. It thus extends the literature and builds on previous research to reframe the concept of authenticity (Grayson & Martinec, 2004; Morhart, Malär, Guevremont, Girardin, & Grohmann, 2015; Napoli, Dickinson, Beverland, & Farrelly, 2014). From a managerial standpoint, our findings should help SMIs manage their authenticity under threat as it suggest that they can either use Passion or Information. SMIs should be cautious to report the reality of the partnership and the product in their WOMM contents. Similarly, they should keep producing noncommercial messages about brands they are really passionate about. In the same vein, managers should be attentive to let SMIs select products in order to increase enthusiasm for the brand and minimize constraints to give room for personalized communication aligned with SMI’s style and opinions.