This chapter shows the physicochemical composition of spinach by-products, the phytochemical compounds, and the potential uses of spinach by-products in food industries. The results indicate that the spinach leaf is rich in minerals and sugars. Interestingly, these findings suggest that spinach extract constitutes a high concentration of phytochemical compounds consisting mainly of chlorophyll and lutein pigments. There are many extracted methods of these compounds, such as conventional maceration, supercritical carbon dioxide, ultrasonic process, and drying techniques. Therefore, the results reveal that supercritical carbon dioxide is the most preferable technique for chlorophyll and lutein extractions. Besides, spinach extracts were incorporated into food products such as cheese, juices, beverages, cereal products, and pasta.