Various slow-release fertilizers (SRFs) have been developed and commercialized, particularly over the past two decades, with the primary aim of mitigating environmental issues associated with excessive fertilizer use. A range of methodologies, including chemical and physical reactions, incorporation into carriers with porous and layered structures, and coating techniques, have been explored and refined. On the other hand, dry and desertification are big challenges for agriculture in many countries in the world. Application of hydrogels or superabsorbent polymers as carrier materials to develop SRFs could add the function of moisture retention. This paper reviewed the development of application eco-friendly starch hydrogels as fertilizer carrier and water retention to develop SRFs, in particular starch-based superabsorbent polymers through grafting copolymerization with acrylamide. The reviewer includes both scientific issues like general microstructures of various starch hydrogels and releasing mechanisms, and technical development involving copolymerization technologies, multi-initialization and loading fertilizer into hydrogel etc. Starch, recognized as one of the most abundant carbohydrate polymers, is both biodegradable and renewable. It exhibits excellent chemical stability and high reactivity. The fabrication technique of starch hydrogels though grafting polymerization have been developed from batch chemical reaction in aqueous solution to high efficient and no-solvent reactive extrusion. The benefits of SRFs based on starch hydrogel encompass enhanced soil aeration, prevention of soil deterioration, minimization of water evaporation, environmental pollution control, reduction in plant mortality, and prolonged nutrient retention within the soil. Based on the literatures and our experience, we have not only discussed and summarized the achievements, but also pointed out the weakness of current technologies and proposed research directions in this review.