Abstract This article interrogates how TikTok has become a voice of authority in the self-diagnosis of ADHD and builds on theories of social, cultural, and algorithmic authority, to offer a theoretical framework of “techno-cultural authority”. Through a digital ethnography and analysis of ADHD TikToks and the technological infrastructures and assemblages surrounding the TikTok app, I demonstrate how ADHD TikTok content creators adopt visual and discursive norms from other trending TikTok content and traditional visual media content to generate authority, and to ensure their videos are deemed viewable and relevant by viewers and the algorithm. Contrary to traditional understandings of medical authority, I find that authority on TikTok is not produced by individuals or institutions, but rather by content creators who engage, en masse, with the supporting technologies of the TikTok app to reproduce familiar trends and visual norms.