Hailey-Hailey disease (HHD) is a rare autosomal dominant genodermatosis that typically presents in mid-adulthood but may be underrecognized in older patients with atypical or late-onset disease. We report a 71-year-old woman with no family history who presented with a one-year history of painful, malodorous intertriginous erosions refractory to standard therapies. Histopathology confirmed HHD, demonstrating suprabasal acantholysis with a “dilapidated brick wall” pattern. Her course was complicated by Staphylococcus aureus and HSV-2 superinfection, which improved with targeted antimicrobial therapy. Due to persistent disease activity, dupilumab was initiated, resulting in rapid and sustained clinical improvement with near-complete resolution at one month and continued remission at six months. This case highlights the diagnostic challenge of late-onset HHD and supports dupilumab as a promising therapeutic option for refractory disease.