Biopolymer hydrogels are synthesized from natural polymers such as chitosan, alginate, cellulose, and starch, each contributing distinct functional properties. Chitosan provides antimicrobial and film-forming abilities, alginate ensures ionic crosslinking and gel stability, and cellulose enhances structural reinforcement and water retention, while starch offers biodegradability and tunable swelling capacity, collectively making these hydrogels promising sustainable materials for agri-food systems. These hydrogels are synthesized through cross-linking strategies such as chemical grafting and ionic interactions, which impart tailored network architectures. As a result, they exhibit remarkable water retention (up to 400× their dry weight) and controlled-release capabilities, positioning them as effective materials for soil conditioning and nutrient delivery. Recent studies have demonstrated the efficacy of biopolymer hydrogels in agriculture, particularly in improving soil and nutrient management. For example, crosslinked xanthan guar gum hydrogels sustained soil water retention across 12 wet and dry cycles, while starch polyacrylamide hybrids increased nitrogen use efficiency in wheat by 20 to 30 percent and reduced fertilizer leaching. In food systems, chitosan–thyme oil hydrogel coatings extended the shelf life of fresh-cut fruits by 3–5 days by mitigating moisture loss and oxidative spoilage, and alginate-chitosan encapsulation boosted probiotic survival by 2–3 log units during digestion. Environmental benefits include a 30–50% reduction in greenhouse gas emissions compared to synthetic polymers, alongside biodegradability and waste valorization potential (e.g., dairy by-products acid whey used in hydrogel synthesis). Future research should prioritize large-scale field trials to validate long-term agroecological impacts and optimize cost-effective production methods for global scalability. Despite challenges like variable mechanical strength, advancements in stimuli-responsive (pH/temperature-sensitive) hydrogels and precision agriculture integration promise to further optimize their performance. Collectively, biopolymer hydrogels represent a transformative approach to sustainable agri-food systems, balancing ecological and economic demands while aligning with global sustainability goals.