<p>Amid rising adult ADHD diagnoses in recent decades, this article introduces a cultural ecosocial niche theory of adult ADHD, suggesting that symptoms emerge within specific cultural and social contexts rather than solely from neurobiological differences. Through in-depth interviews with seven Australian women recently diagnosed with adult ADHD, complemented by photo-voice methodology, we show how ADHD symptoms fluctuated markedly across different social interactions. The study found that participants actively construct and inhabit cultural ecosocial niches where their traits achieve a functional fit with their social and cultural environment. These niches ranged from adopting the macro-cultural framework of ‘neurodiversity’ to build affirming identities and communities, to finding micro-social occupational niches in fast-paced roles where their cognitive style became an advantage. Each niche was sustained by a reinforcing feedback loop, where the environment (such as a supportive social group or a demanding job) reinforced the very traits and beliefs that initially attracted them to that niche. This study challenges the notion that psychiatric symptoms are confined solely within a person or solely outside in the environment. Instead, it provides a concrete example of how symptoms and their meanings appear at the intersection of both. These findings illuminate the complex ways socio-cultural settings can both constrain and empower, while highlighting implications for how we conceptualise and address adult ADHD in an era of increasing diagnosis.</p>