Date kernel powder is one of the waste products of the agricultural sector and food industry, which, after processing, can be used as a functional additive to constitute part of human and animal food. Date kernel powder contains significant amounts of dietary fiber, a component which has an important role in disease prevention. Because Iran is one of the major producers of dates in the world and because of the nutritional value of date kernel, its use as a byproduct of the date industry in human and animal nutrition has attracted much attention. Phenols are beneficial compounds in the date kernel that usually show high antioxidant activity. The purpose of this study was to determine nutritional values and amounts of functional compounds in cake enriched with date kernel powder and to investigate changes in some important physicochemical properties of the new product and its acceptability by consumers. Date kernel powder in amounts of 5% and 10% was added to sponge cake formulation and compared with the control sample in terms of texture (hardness, cohesiveness, gumminess, flexibility, elasticity, and chewiness), antioxidant properties (total phenol content and DPPH free radical scavenging), drainage rate, as well as mineral salts, protein, fat, and fiber content and sensory evaluation. The results showed that different levels of date kernel powder have a significant effect on the level of gumminess, hardness, and cohesiveness. The amount of total phenol, and consequently the percentage of free radical scavenging, as well as minerals, protein, and fiber content, increased with the increase in the amount of date pit powder in the sponge cake. The results of the tests showed that 10% date kernel powder in sponge cake has the highest level of overall acceptability in terms of sensory evaluation. It is concluded that date kernel powder has high amounts of fiber, protein, and minerals content, as well as a high level of antioxidant activity, and has a good potential as a valuable and economical food ingredient to be used in food products and can be used in food formulations and also as a functional food.