<p>Drought is the primary and most pervasive environmental stress that plants face, and it has the potential to cause significant harm to crops. Selenium (Se) possesses various advantageous characteristics that comprise promoting plant growth, augmenting crop resistance to oxidative stress, and retarding senescence. Here, we investigated the combined effect of drought stress and Se on the growth, physiology, yield and quality of quinoa. Se was applied as a foliar application (Se₀ = 0 mg L^− 1 Se, Se₁ = 10 mg L^− 1 Se, Se₂ = 15 mg L^− 1 Se, Se₃ = 20 mg L^− 1 Se) to quinoa plants grown under drought conditions (control, drought at multiple leaf stage, drought at flowering stage, and drought at grain-filling stage). Drought stress significantly reduced the growth and yield-contributing parameters, antioxidant enzyme activity, physiological attributes and quality parameters. However, Se foliar application mitigated the adverse effects of drought by improving leaf area index (20.53%), crop growth rate (15.55%), leaf chlorophyll contents (26.47%), water use efficiency (16.28%), phenolics (11.25%), peroxidase (27.30%), superoxide dismutase (30.72%), glutathione peroxidase (12.46%), catalase (29.68%) activities, economic yield (16.51%), and grain protein contents (4.23%). The best-suited concentration to improve the growth, yield and nutritional quality of quinoa under drought conditions was found to be 15 mg L^− 1. This study highlights the potential of Se foliar application in enhancing the resilience of quinoa to drought stress.</p>