The California condor (Gymnogyps californianus) is a highly endangered scavenging bird that has been subject to many anthropogenic challenges in its free-living environment, including lead toxicosis, trash ingestion, powerline collisions, and gunshots. In March 2023, during a highly pathogenic avian influenza hemagglutinin 5 neuraminidase 1 (HPAI H5N1) outbreak, California condors in Northern Arizona were presented to a wildlife rehabilitation center and found to be infected with HPAI H5N1 clade 2.3.4.4b, genotype A3. Eight birds in total entered the facility with variable signs, including hyporexia, corneal edema, weakness, reduced body condition scoring, and seizure activity. Seven (87.5%) of 8 birds tested positive by reverse-transcription polymerase chain reaction assay for HPAI, and 5 (62.5%) had avian influenza hemagglutinin 5 (H5) antibody titers, which were considered highly confident as an indicator of prior H5 avian influenza virus exposure. Additional biochemical, infectious disease screening, and toxicologic tests were also performed. Supportive care treatments consisted of fluid support, vitamin B complex, meloxicam, and oseltamivir (Tamiflu). Plasma oseltamivir concentrations were measured in 2 individuals receiving the medication. The outcomes of individual patients are described in this report, with 4 (50%) birds surviving.