This study aims to investigate the chemical constituents of Chaenomeles speciosa (Sweet) Nakai leaf and evaluate their antioxidant, whitening and uric acid-lowering activities. The chemical composition of the methanol extract of C. speciosa leaf (MECL) were identified by gas chromatography-mass spectrometry (GC-MS). The uric acid-lowering effects of MECL in a hyperuricemia mouse model, as well as its antioxidant and whitening activities were evaluated using the DPPH assay and B16/F10 melanoma cells. Additionally, the mechanisms underlying its whitening and uric acid-lowering effects were explored. The results revealed that seventeen compounds, including oleanolic acid, ursolic acid, linoleic acid, stearic acid, squalene, and vitamin E, were identified in MECL. In vivo, MECL significantly reduced serum uric acid levels by 48.5% in hyperuricemic mice at 500 mg/kg and inhibited xanthine oxidase with IC₅₀ at 5.628 mg/mL. On the other hand, MECL inhibited melanin production in B16/F10 cells by 32.49% at 50 μg/mL and exhibited potent tyrosinase inhibitory activity with IC₅₀ at 9.112 mg/mL. Furthermore, MECL displayed remarkable strong DPPH free radical scavenging activity with an EC₅₀ value of 46 μg/mL, and alleviated hyperuricemia-induced liver and kidney damage in mice without cytotoxicity. In summary, MECL exerts effectively lowering uric acid in vivo by inhibiting the key enzyme xanthine oxidase and enhancing whitening in vitro by suppressing the key enzyme tyrosinase in B16/F10 cells with strong free radical scavenging activity. These findings highlight its potential for functional and health food applications.