Although Prussian blue has been one of oldest coordination compound with variety of biocompatible applications however their use has been limited to only non-processable electro-synthesized film due to uncontrolled nucleation during chemical synthesis of the same. The current finding report the synthesis of three types of processable Prussian blue nanoparticles in both homogeneous and heterogeneous matrix. These processable Prussian blue nanoparticles of controlled nanogeometry and plasmonic activity has been explored for the detection and efficient removal of ¹³⁷Cs radionuclides from contaminated water. Prussian blue nanoparticles of three different nanogeometry (PBNP-1, PBNP-2, PBNP-3) was made from single precursors, potassium hexacyanoferrate in the presence of three different reagents that allowed controlled nucleation and stabilization of Prussian blue nanoparticles of variable plasmonic activity as a function of functionality associated to the stabilization of Prussian blue nanoparticles. Further as made Prussian blue nanoparticles were characterized by TEM, XRD, UV-VIS spectroscopy and electrochemical measurement. Similar process was used to synthetically incorporate Prussian blue nanoparticles within mesoporous silica and characterized by XRD. Prussian blue nanoparticles inserted mesoporous silica was used for selective adsorption of ¹³⁷Cs followed by detection of radioactivity. Based on the measurement of radioactivity before and after ¹³⁷Cs adsorption, distribution coefficient K_d for cesium nuclides was calculated to be 3.2x10⁵ ml.g^-1 displaying both Langmuir and Freundlich adsorption Isotherms. The dependence of Cesium adsorption on Prussian blue nanogeometry was evaluated based on cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. The plasmonic activity of Prussian blue nanoparticles has enabled fluorescent probe mediated fluorescence sensing of Cesium ion. The effective plasmonic coupling of as made functional Prussian blue nanoparticles with fluorescence probe resulted fluorescence sensing of cesium ion regulating the spatial control between the functional Prussian blue nanoparticles and fluorescence probe molecule serving as promising platforms for Prussian blue nanoparticles enhanced fluorescence and fluorescence resonance energy transfer based chemical sensing