One of the major factors significantly modifying plant physiology and ultimately causing a loss in crop productivity is water deficiency stress. Plant-based pigments are highly effective in enhancing growth and reducing the consequences of water stress. The present study aimed to identify the effects of copper chlorophyllin (Cu-Chl) at rates of 0, 1, and 2% on the growth, yield, and physiological traits of spinach plants of the variety Viroflay grown under three irrigation levels of 100%, 75%, and 50% crop evapotranspiration rates (ETc) in the 2020 and 2021 growing seasons. In comparison with full irrigation (100% ETc), deficit irrigation with 50% ETc drastically reduced plant growth parameters (height, leaf number, leaf area, and fresh and dry weight), yield, relative water content (RWC), leaf membrane stability index (MSI), electrolyte leakage (EL), chlorophyll a, chlorophyll b, carotenoids, Fe, and Cu content. However, the nitrate and oxalate content increased in the plants. All studied values were significantly higher except nitrate and oxalate content which were lower with Cu-Chl application, in comparison with those without Cu-Chl application. The present work demonstrated that the adverse effects of water deficit on growth, yield, plant water status, and photosynthetic pigments of spinach plants could be alleviated when using Cu-Chl application.