A large amount of radioactive cesium (Cs) has been released into natural environment following the nuclear accident in Fukushima, Japan in 2011. Much effort has been directed at capturing Cs and remediation of the contaminated environment. However, conventional sorbents such as Prussian blue and zeolites cannot be easily recovered once spread into an open environment. Here, we develop new nano-sorbent based on magnetic nanoparticles (MNP) functionalized with Prussian blue (PB) that possess both high Cs adsorption capacity (98 mg Cs/g sorbent) and large distribution coefficient (3.2 x 104 mL/g at 0.5 ppm Cs concentration). The developed sorbents possess good value of saturation magnetization (20 emu/g) allowing for rapid and ease of sorbent separation from the Cs solution after treatment using magnetic field. This Cs magnetic nano-sorbent can offer high potential for use in large scale remediation of a Cs contaminated environment as well as the possibility of novel Cs decorporation drugs that can be magnetically assisted for accelerated excretion of radiocesium from the human body.