A study was conducted in Akure, South West Nigeria on the effect of wood ash, ground cocoa husk, spent grain, saw dust and rice bran, either raw or amended with animal manure on the growth, leaf nutrient contents and yield of four crops of Amaranthus viridis (L). Twenty combinations of agro-industrial biomass were applied to the soil together with one treatment with NPK fertilizer and a control which received no treatments. The agroindustrial biomass was applied at t/ha or individually combined with goat, pig and poultry manures at the rate of 3tha-1 (1:1 ratio). The twenty two (22) treatments were replicated four times on each of the four consecutive crops using a randomized complete block design. Results showed that the application of agro-industrial biomass to the soil increased the leaf N,P,K,Ca, Mg ash, Crude protein, plant height, leaf area, stem girth and leaf yield of amaranthus significantly (p<0.05) compared to the control treatment Application of spent grain, cocoa husk and wood ash was more effective in increasing growth, leaf N, P, K, ash and crude protein, and leaf yield of amaranthus than the rice bran and sawdust. The spent grain treatment increased the leaf N, P, K, Ca, Mg, ash and crude protein of amaranthus by 32.4%, 22%, 30%, 21%, 15.3%, 32% and 6% respectively compared to the rice bran (sole) application. Incorporation of animal manure with agro-industrial biomass further increased the leaf yield. Wood ash + poultry manure treatment increased the amaranthus leaf yield by 67%, 50%, 35% and 34 % respectively in crops 1, 2, 3 and 4 compared to the sole application of spent grain. Treatments with agro-industrial biomass gave higher leaf K, Ca, and Mg contents compared to NPK fertilizer except the leaf yield. In addition, amendment of spent grain with poultry manure also increased the leaf N, P, K, Ca, Mg, crude protein and ash or amaranthus by 12%, 34%, 17.40%, 96.30%, 93%, 48% and 26% respectively compared to the NPK treatment. The amended wood ash, cocoa husk, rice bran, spent grain and sawdust with poultry manure increased the root length of amaranthus by 47%, 42%, 41.58%, 53% and 27% respectively compared to NPK fertilizer treatment. Addition of agro-industrial biomass either alone or incorporated with animal manure increased the nutrient content in the leaf and yield of Amaranthus progressively over the four cropping seasons. The R2 values of the relationship between amaranthus leaf yield and leaf N,P, K, Ca, Mg, Na, crude protein andash were 0.90, 0.92, 0.94 and 0.98 in crops 1, 2, 3 and 4 respectively. The implication is that leaf nutrients accounted for 90%, 92%, 94% and 98% variations in leaf yield of amaranthus.