<p>Biodegradable superabsorbent hydrogels have been proposed as soil conditioners to mitigate agricultural water stress, yet evidence on their agronomic relevance and environmental safety remains fragmented and contradictory. This review synthesizes current knowledge across five domains: material composition, swelling performance, biodegradation, field-scale application, and economic viability. A recurring performance–sustainability paradox is identified, whereby formulations that improve swelling stability and durability often compromise biodegradability, while environmentally benign designs show poor persistence and limited field efficacy. A critical analysis reveals a systematic overestimation of performance in laboratory studies relative to field conditions. Swelling capacities measured in distilled water are often 5–10 times higher than those realized in field soils, and biodegradation studies predominantly rely on indirect proxies rather than confirming complete mineralization, leaving ecological risks unresolved. Field application techniques, such as broadcasting, incorporation, and seed coating, provide localized benefits but lack scalability. Meanwhile, high production costs and incomplete life cycle assessments undermine claims of sustainability. Unlike earlier descriptive reviews, this study offers a critical integrative synthesis across technical, agronomic, ecological, and economic dimensions. Future progress depends on whole-system frameworks that incorporate standardized agro-climatic testing, isotopic tracing, and metagenomic monitoring of biodegradation, mechanized delivery technologies, and life cycle assessment. Such interdisciplinary validation is essential for harmonizing performance with sustainability and advancing BSAHs from experimental prototypes to credible tools for climate-resilient agriculture.</p>