Pressmud, a by-product of the sugar industry, is rich in organic carbon and nutrients. This study explores the eco-design of pressmud-based organic blends integrated with biochar, vermicompost, and microbial inoculants to restore the fertility of nutrient-depleted soils. Through laboratory and field experiments, we assessed physicochemical properties, microbial activity, and crop response. The results demonstrate a significant improvement in soil health, increased organic carbon, and yield enhancements in crops such as maize and pulses. This research offers a sustainable waste valorization approach aligned with circular economy principles and environmental management. The degradation of agricultural soils due to intensive farming practices and excessive chemical input has led to widespread nutrient depletion, affecting crop productivity and ecological balance. This study presents an eco-design approach to formulate organic soil amendments using sugar industry pressmud, in combination with biochar, vermicompost, and microbial inoculants. Through laboratory characterization and field trials, we evaluated the blends' effects on soil physicochemical properties, microbial biomass, and crop yield performance. Results indicated significant improvements in organic carbon content, nutrient availability (NPK), microbial activity, and crop productivity compared to control treatments. The most effective blend—combining pressmud, biochar, and beneficial microbes—achieved up to 40% higher soil organic carbon and a 37% increase in crop yield. This eco-designed approach not only valorizes agro-industrial waste but also supports sustainable soil management and circular agricultural practices. The findings demonstrate the potential of pressmud-based blends as viable biofertilizers for the rehabilitation of nutrient-depleted farmlands.