The present study presents a comprehensive analysis of effects of porous fins on mixed convection heat transfer in lid-driven square cavities, where the top lid has the two-way movement. Porous medium with varying permeability, instead of the solid one, could widely modify its baffling effect on fluid flow and could also be utilized to control fluid flow and heat transfer. Fluid flow within the cavity was solved through the Navier-Stokes equations, while that within a saturated porous medium was governed by the Darcy-Forchheimer model. Numerical results indicate that the adding porous fins with excellent permeability could enhance heat transfer dramatically, especially for more fins. The rate of heat transfer enhancement due to an increase in Darcy number decreases, and similar trends were observed for the quantitative variations of porous fins. Besides, positions of porous fins have significant effects on fluid flow and heat transfer. The correlations of average Nusselt numbers, as functions of various governing parameters, have been proposed. The present investigations could be beneficial to the design of the microelectronic cooling through the installation of porous-alike materials or modules.