Online spaces have the capacity to be powerful informal learning and identity development spaces for marginalized communities. However, there is still much work to be done to uncover these complex social identities using ethical big data analyses. In this study, I draw on the theory of Knowledgeable Agents of the Digital, data feminism, and critical reflexivity practices to engage with a #blackgirlmagic Twitter dataset from 2016 to 2019. Using Epistemic Network Analysis, findings suggest that the #blackgirlmagic community self-defined their social identities around Black beauty, academic/professional accomplishments, and social justice. Because the women and girls of #blackgirlmagic were agentive in rewriting and sharing narratives of themselves, they were acting as knowledgeable agents of the digital. These findings may be useful for (1) uncovering other instances of knowledgeable agents from non-dominant populations and how they navigate a racialized and gendered society, and (2) providing suggestions for analyzing online big data through an ethical, intersectional feminist lens.