The Musca domestica antifungal peptide-1A (MAF-1A peptide) from housefly larvae was synthesized by solid-phase synthesis technique, and antiviral, antioxidant, and antifungal properties were evaluated in this study. Present results indicated that it could significantly inhibit the infection of influenza virus H₁N₁, Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), and Bombyx mori nuclear polyhydrosis virus (BmNPV), which displayed excellent virucidal activities. Antioxidant results demonstrated that the MAF-1A peptide had effective scavenging activity for hydroxyl and superoxide radicals, which were similar to that of ascorbic acid. Besides, antifungal results showed that it can also significantly inhibit the growth of four fungi, and the half inhibitory concentrations (IC₅₀) values were ∼59.3, 84.2, 144.9, and 48.5 μg/ml, respectively, highlighting an important role of MAF-1A peptide in the defense of M. domestica against pathogenic microorganisms. These results revealed that the MAF-1A peptide from housefly larvae has great potential as a natural ingredient for the exploitation of antiviral and antifungal therapeutic agents, avoiding abuse of chemical agents and environmental pollution.