This study investigated the effect of 3 biochar application rates (1%, 5%, and 10%) on the pH, surface charge, and bioavailability of Cu, Pb, Zn on a degraded Acrisols soil and their accumulation in water spinach (Ipomoea aquatica). After an incubation period of 28 days, a titration experiment confirmed that increasing the biochar application rates enhanced the negative charge along with an increased pH. In an experiment spiked with metals, the 0.01 M CaCl2-extractability of the metals after incubation significantly decreased with the increasing rate of biochar additions. This is mostly attributed to a rise in the soil pH and an increase in the negative charge as result of the biochar additions. Metal extractability continued to decrease over the next 1,344 h, most probably due to the aging effect. Immobilization speeds exhibited in the order Pb>Cu>Zn, can be partially attributed to the bigger ionic radius of Pb compared to those of Cu and Zn. By the end of incubation period, extractable Cu, Pb and Zn was significantly reduced, irrespective rates of biochar application 1%, 5% or 10%. In a greenhouse experiment, water spinach was unable to grow in the 10%biochar addition because of a high alkaline pH of 9.2. The Cu, Pb, and Zn concentrations and bioaccumulation factor in the grown water spinach decreased along with the increasing biochar application rates in the order 5%>1%>0%, showing a good agreement with the 0.01 M CaCl2-extractable concentrations. The bioaccumulation factors of Pb were far less than those of Cu and Zn, reflecting the immobilization speeds as concluded in the incubation tests. Therefore, biochar amendment into degraded soil for metal immobilization is feasible, provided the appropriate rate for crop growth is applied.