This article looks at the social and cultural contexts of children's experiences of illness, through a particular focus on the context of the Global South and the role of the social media platform YouTube in children's culture. It takes a socio-constructivist approach to discuss the case of "CarecaTV" (BaldTV), a Brazilian YouTube channel with more than one million followers created by Lorena Reginato at the age of 12 when she was recovering from brain cancer. In CarecaTV, cancer subjectivity co-exists with and is expressed through digital commercialization. On the one hand, through this process, Lorena Reginato gains agency as she offers an inspirational and credible first-person testimony about cancer during childhood and becomes an emerging cancer activist. On the other, she uses entrepreneurship strategies associated with the digital influencer model of YouTube to promote herself as a (cancer) micro-celebrity, taking the lead in a youthful and playful culture.