<p>Orthorexia nervosa (ON) is increasingly understood as a morally saturated health orientation in which dietary restraint is organised through ideals of purity, discipline, and self-worth. Building on social theory that treats health as a cultural project and a site of identity governance, this study theorises ON as moral identity work enacted and contested in digital environments. Using a large-scale qualitative design integrating thematic corpus mapping and Critical Discourse Analysis (CDA), 1,100 texts from Reddit, YouTube, and blogs (2020–2025) were analysed; an intensified CDA subset (n=80) traced how key meanings were rhetorically accomplished. Across platforms, moralised purity/contamination vocabularies and identity-relevant self-positioning were common but genre-sensitive. In the CDA subset, a recurring configuration framed restrictive eating as (a) morally evaluative, (b) identity-defining and non-negotiable, and (c) defended via boundary work and resistance to pathologisation; recovery narratives more often disrupted these binaries and decoupled selfhood from dietary purity. Extending existing accounts that document morality narratives around ON, the analysis specifies the discursive mechanisms and genre- and platform-sensitive configurations through which moralisation becomes identity-defensive and resistant to critique. These findings clarify the discursive mechanisms through which ON becomes intelligible and defensible within digital wellness culture, with implications for prevention and care focused on moralised self-concept and digitally reinforced rigidity.</p>