Ultrasound-assisted extraction (USE) was used to extract the water-soluble components of corn silk, and the resulting corn silk water extract (CSWE) was tested for DPPH• and OH• radical scavenging activities and subjected to reducing power evaluation. In addition, the uric acid-lowering effects of CSWE were investigated through mouse experiments, where the body weight, serum uric acid (SUA) levels, and kidney pathologies of the mice were observed. CSWE (C3 group) exhibited significant DPPH• and OH• activities (90.75% and 86.29%, respectively) and reducing power (P<0.05), indicating that CSWE has immense antioxidative potential. Four weeks of gavage with CSWE decreased the body weight and SUA levels and improved the kidney tissue health of hyperuricemic mice. The high CSWE (HCS) group in particular, showed significant improvements in their SUA levels (decreased to 726.26 μmol/L, P<0.05), organ indices (0.60%), and kidney tissue health. Therefore, CSWE has outstanding antioxidant and uric acid-lowering activities, and it could potentially be marketed as a functional food for preventing oxidative injury and hyperuricemia.