The emergence of highly pathogenic avian H5N1 influenza viruses in dairy cows and humans has increased the potential for another pandemic. To address this risk, we developed chimpanzee adenoviral (ChAd)-vectored H5 hemagglutinin-targeted vaccines and tested their immunogenicity and efficacy in rodents. Immunization with ChAd-Texas (clade 2.3.4.4b) vaccine in mice elicits neutralizing antibody responses and confers protection against viral infection and mortality upon challenge with a human H5N1 isolate (A/Michigan/90/2024, clade 2.3.4.4b). Intranasal delivery of the ChAd-Texas vaccine elicits mucosal antibody and T cell responses and confers greater protection than intramuscular immunization. In Syrian hamsters, a single intranasal dose of ChAd-Texas vaccine prevents weight loss and reduces airway infection after H5N1 A/Michigan/90/2024 or A/Texas/37/2024 challenge. Importantly, prior seasonal influenza vaccination does not impair antibody responses or protection after intranasal delivery of the ChAd-Texas vaccine. These results support the development of mucosally administered ChAd-Texas HA vaccines as an effective platform for HPAI H5N1 preparedness.