The global burden of influenza virus and rhinovirus, along with significant mortality and severe case reports, underscores the urgent need for new antivirals. Human defensins serve as the first line of defense against viruses; however, the antiviral activity of defensin peptides is often sensitive to salt, which affects their effectiveness. This study investigates a branched human-defensin peptide H30 (4H30) that can more effectively inhibit influenza virus and rhinovirus compared to the linear form of H30. Mechanistic studies reveal that 4H30 binds to influenza HA to aggregate the virus, thereby blocking viral entry. 4H30 can also cross-link H1N1 virus with cell surface glycosaminoglycans to prevent viral release. The dual-functional peptide 4H30 protects mice from the lethal challenge of the A(H1N1)pdm09 virus, demonstrating a high barrier to viral resistance after 15 viral-culture passages in the presence of 4H30. Notably, 4H30 interferes with the low-density lipoprotein receptor (LDLR) to impede the entry of minor group rhinovirus and significantly inhibits rhinovirus replication in RD cells, nasal organoids, and stem cell-derived cardiomyocytes. These findings suggest that the branched peptide 4H30, targeting both the virus and host, can more effectively inhibit influenza and rhinovirus than the linear H30, providing a new avenue for antiviral peptide development.