Abstract: To address the bottleneck restricting yield and quality improvement of cucumber (Cucumis sativus L.) in protected cultivation, this study explored the effects of laser irradiation, graphene oxide (GO) root drenching, and their interaction on photosynthetic physiology, yield, and fruit quality. The aim was to provide seasonal regulation strategies for protected cucumber production. Two-season (spring and autumn) experiments using coconut coir substrate cultivation were conducted from March to November 2025 in Xindu District, Chengdu City, Sichuan Province, using the cucumber cultivar ‘Qingbai Zao’. Treatments included laser irradiation (13 W red-blue laser lamp, daily irradiation from 08:00 to 18:00) and root drenching with graphene oxide (GO) at concentrations of 0.00, 0.25, 0.50, and 1.00 mg/L, comprising both single-factor and combined treatments. Photosynthetic physiology, yield, and fruit quality indexes were measured, and analysis of variance was performed to test the main and interactive effects of experimental factors. The results showed that differences in light conditions were a key environmental factor driving seasonal variations in cucumber growth, yield, and quality. In spring, the average net photosynthetic rate, yield, and vitamin C (Vc) content under different treatments reached 27.24 μmol/(m²·s), 6621.0 kg/667 m², and 8.12 mg/100 g, which were 94.7%, 107.3%, and 112.0% higher than those in autumn, respectively. The average soluble sugar content of cucumber fruits across treatments in spring was 1.06%, which was 61.7% lower than that in autumn. Under single laser-irradiation treatment, cucumber yield increased by 2.5%–7.3% in spring and 4.6%–10.9% in autumn relative to the non-laser control. Single GO root drenching had no significant effect on cucumber yield, yet significantly modified fruit soluble sugar and Vc contents. The maximum increase rates of soluble sugar content reached 12.1% in spring and 45.3% in autumn; the maximum increase rates of Vc content were 7.7% in spring and 45.0% in autumn. The interaction between laser irradiation and GO exhibited obvious seasonal dependence. Their interaction showed no significant influence on net photosynthetic rate and yield in spring, but was significant (P < 0.05) for these parameters in autumn. Their interactive effects on soluble sugar and Vc contents were extremely significant (P < 0.01) in both seasons. Based on these findings, seasonal regulation strategies are proposed: single laser irradiation for spring cultivation, and a combined treatment of laser irradiation plus 0.25 mg/L GO root drenching for autumn cultivation. This study provides a theoretical basis and practical reference for the joint application of light regulation and nanomaterials in protected agriculture.