The study evaluated the metal immobilizing impact of chicken manure- and green waste-derived biochars on soil and their effectiveness in promoting plant growth. The results showed that biochar application significantly reduced the extractable concentrations of Cd, Cu, and Pb, indicating metal immobilization. Chicken manure-derived biochar increased plant dry biomass by 353% and 572% for shoots and roots, respectively, with a 1% addition. Both biochars reduced the accumulation of these metals in Indian mustard (Brassica juncea), with the reduction increasing with higher biochar application rates. Metal sequential fractionation data indicated that biochar treatments modified the partitioning of metals from easily exchangeable to less bioavailable organic-bound fractions. The findings suggest that biochar application is effective in reducing the bioavailability and phytotoxicity of heavy metals.The study evaluated the metal immobilizing impact of chicken manure- and green waste-derived biochars on soil and their effectiveness in promoting plant growth. The results showed that biochar application significantly reduced the extractable concentrations of Cd, Cu, and Pb, indicating metal immobilization. Chicken manure-derived biochar increased plant dry biomass by 353% and 572% for shoots and roots, respectively, with a 1% addition. Both biochars reduced the accumulation of these metals in Indian mustard (Brassica juncea), with the reduction increasing with higher biochar application rates. Metal sequential fractionation data indicated that biochar treatments modified the partitioning of metals from easily exchangeable to less bioavailable organic-bound fractions. The findings suggest that biochar application is effective in reducing the bioavailability and phytotoxicity of heavy metals.