Summary: Background: Onychomycosis affects almost 6% of the world population. Topical azoles and systemic antifungal agents are of low efficacy and can have undesirable side effects. An effective, non‐invasive therapy for onychomycosis is an unmet clinical need.Objective: Determine the efficacy threshold of non‐thermal atmospheric plasma (NTAP) to treat onychomycosis in an in vitro model.Methods: A novel toe/nail‐plate model using cadaver nails and agarose media inoculated with Candida albicans was exposed to a range of NTAP doses.Results: Direct exposure of C albicans and Trichophyton mentagrophytes to 12 minutes of NTAP results in complete killing at doses of 39 and 15 kPulses, respectively. Onset of reduced viability of C albicans to NTAP treatment through the nail plate occurs at 64 kPulses with 10× and 100× reduction at 212 and 550 kPulses, respectively.Conclusions: NTAP is an effective, non‐invasive therapeutic approach to onychomycosis that should be evaluated in a clinical setting.