Chapter 13 Social media influencer: a new hybrid professionalism in the age of platform capitalism? by P. Sedda and O. Husson, analyses the way social media influencers, acting in the context of communities of practice, participate in redefining professionalism and professional practices in marketing and communications fields while promoting social values or advocating for a cause of public interest. Using a methodological approach based on interviews and ethnographic observation, the study considers the influencer as a specific case of “hybrid professionalism” (Noordegraaf 2007) in which quantitative performance criteria, prescribed by platforms, are combined with creative logic and collective action. Centred on the promotion of authenticity and individual achievement, their commitment evokes the figure of “artistic critique” (Boltanski and Chiapello 2011). If they claim recognition and expertise, these actors do not necessarily engage in a real process of institutionalisation as the influence they exert among their communities mainly derives from their differentiation from institutional actors allowing for better visibility of messages of social change. In an effort to go beyond traditional approaches, our perspective looks at professionals as actors of change who are constantly reframing their discourse on “professionalism” on the basis of public demands and the emergence of new political and societal issues.