The study investigates the linear and weakly nonlinear stability of Jeffrey fluids in an anisotropic porous medium with throughflow. In the linear stability analysis, the study examines how convective motion changes with variations in the Jeffrey parameter, Peclet number, and anisotropic parameters. The study finds that thermal anisotropy parameter, positive Peclet number, and mechanical anisotropy parameter delay the onset of fluid convection, whereas the Jeffrey parameter enhances the onset of convection in the presence of throughflow. In the nonlinear analysis, heat transfer is calculated using the Ginzburg–Landau Equation (GLE). The study observes that heat transfer increases with the Vadasz number and positive Peclet number, making the system unstable, whereas heat transfer decreases with an increased value of the Jeffrey parameter, thermal anisotropy parameter, mechanical anisotropic parameter, and negative Peclet number, making the system stable.