Applying pesticide in agriculture to protect plants from weeds, fungi, insects etc., become an essential component of farming from the year of 1950 approximately. We know its drawbacks as potential toxicity to humans’ life and so, one of the challenging research is to stop or optimize the pesticide spreading beyond the intended area. In this regard, a controlled release (CR) formulation of a pesticide regulates the diffusion process in controlled manner through the porous matrix or membrane by controlling the release rate of active materials. Present chapter is intended for a quick review on theoretical framework for CR of pesticide by using standard Fick’s law of diffusion. The active substance, for instance a herbicide gets dispersed through a granule and gets released into the soil via diffusion. By solving Fick’s law, we have obtained concentration as a function of space and time for different geometry (boundary condition) like slab and sphere, which can provide the geometrical visualization of controlled release pattern of pesticide. We have also discussed the microscopic picture of diffusion coefficient in the unit of micrometer square per second and diffusion length in the unit of nanometer, which appear as microscopic cause for macroscopic controlled release physics. We have also discussed another advance technique of smart diffusion in low concentration, done by nano-pesticides to minimize non-targeted toxicity.