A sorbent composition for the removal of boron and/or borates from a fluid such as an aqueous medium. The sorbent composition includes a base sorbent material having a high porosity and surface area, and a boron-selective agent. By using a boron-selective agent in conjunction with a high surface area base sorbent material such as activated carbon or biochar, a sorbent composition with a high capacity for sequestering boron and a relatively low cost is provided. The sorbent compositions are particularly useful for the sequestration of boron from waste materials such as coal combustion residual leachate (CCRs).