In this research, we investigate the flow of ternary nanofluids under the influence of magnetic field in converging/diverging channel. The fluid assumed to be viscous, incompressible, and electrically conducting. The effect of Lorentz force on fluid motion is systematically examined. For practical applications, stretching and shrinking channel are considered. Using similarity transformation, the governing partial differential equations (PDEs) are reduced to ordinary differential equations (ODEs), which are then solved numerically with the ND-Solve technique. This method effectively handles the highly nonlinear equations and provides accurate results. The velocity and temperature profiles are presented graphically for various physical parameters, while skin friction and Nusselt number are analyzed. The results reveal that an increase in the magnetic parameter reduces the fluid velocity and enhances the temperature in both convergent/divergent channels. Furthermore, ternary nanofluids exhibit a stronger impact compared to nano and hybrid nanofluids.