<p>This study evaluated the effects and mechanisms of nutrient-enhanced and metabolic-regulating foliar fertilizers on the growth, physiological regulation, stress tolerance, and yield of high-quality japonica rice. Field experiments were conducted in 2023 and 2024 in the Taihu Lake region, China, using two japonica rice cultivars (“Sujing 2148” and “Sujing 4699”) in a randomized complete block design. Treatments included nutrient-enhanced foliar fertilizer (T1), metabolic-regulating foliar fertilizer (T2), combined application (T3), and a control (CK). The combined application (T3) showed significant advantages. In 2023, for Sujing 2148, dry matter accumulation at maturity under T3 reached 20,312.70&#xa0;kg ha^− 1, significantly exceeding T1, T2, and CK by 7.0%, 6.3%, and 8.1%, respectively. Net photosynthetic rate under T3 was 35.48 µmol m^− 2 s^− 1, a 49.0% increase compared to CK. T3 significantly increased gibberellin and indole-3-acetic acid contents, reaching 58.76 ng g^− 1 fresh weight (FW) and 26.37 ng g^− 1 FW, while reducing abscisic acid content to 71.17 ng g^− 1 FW. Stem mechanical strength was enhanced, with bending force of the first internode reaching 10.23&#xa0;N, which represents the maximum force required to bend the stem. Lignin content increasing to 21.30%. Yield components under T3 were significantly improved, with a total yield of 10,743.67&#xa0;kg ha^− 1, 12.6% higher than CK. Results from 2024 validated these trends, confirming the stability of T3. This study highlights that combined foliar fertilizer application enhances photosynthetic efficiency, optimizes hormonal balance, strengthens stem properties, and promotes yield improvement in high-quality japonica rice.</p>