Shiitake mushroom (Lentinula edodes) treated with cold plasma removed up to 82.5% of fenvalerate pesticide residues at 80 kV in 15 minutes, with most degradation occurring within the first 2–5 minutes. Reactive species like •OH, O₃, and H₂O₂ drove chemical breakdown through hydroxylation and bond cleavage, reducing both residue levels and overall toxicity. This process preserves texture, phenolics, and storage quality while eliminating harmful pesticides without heat or chemical washing.