The objective of this investigation is to determine the impact of nonuniform heating on the transient natural convection of Casson fluid past a vertical cone in the appearance of a constant magnetic field. The overall analysis has executed in the presence of viscous dissipation, chemically reactive species, and ramped concentration. The derived governing partial differential equations in the dimensionless form are evaluated numerically using the implicit Crank‐Nicolson technique of finite difference method. The obtained numerical solutions for various physical parameters on all examined profiles have been shown graphically. The major result is found that the temperature and velocity profiles have a maximum magnitude at the middle of the lateral side of the cone. Also, the concentration profile has a maximum magnitude at t = 3 for ramped concentration case.