This study proposes the introduction of quinoa into the cropping structure in sandy soil, through intercropping with onion, as a sustainable solution to mitigate climate change effects. The study was conducted during the two growing seasons 2021/ 2022 and 2022/2023 in Ismailia Agricultural Research Station, ARC, Ismailia governorate, Egypt to investigate the effect of 3 planting dates (4WBT: 4 weeks before transplant onion, 2WBT: 2 weeks before transplant onion, and AST: at the same time of transplant onion) and 3 plant spacing of quinoa (10, 20 and 30 cm) intercropped with onion on the productivity of the two crops, quality traits in quinoa, and the farm's income. Results indicated that planting quinoa 2WBT at 10 cm had the highest grain yield of quinoa, while planting date at 4WBT had the maximum values of quinoa quality traits by planting quinoa at 30 cm for grain protein content and 10 cm for saponin. In addition, the highest yield of the onion produced by planting quinoa 4 WBT at spacing of 30 cm. The highest values of LER (1.46 and 1.42) and total and net income produced by intercropping quinoa at planting date 2 WBT and 10 cm spacing in first and second season, respectively. Despite onion price fluctuations in both seasons caused by climate change (rainfall), and impacting output, intercropping quinoa with onion produced a higher and more stable financial return than sole onion cultivation in either season. Accordingly, it can be introducing quinoa into cropping structure in sandy and marginal soils by intercropping quinoa 2 weeks before transplanting onion at a plant spacing of 10 cm to increase land equivalent ratio and net income for Egyptian farmers than onion sole cultivation.