Efficient thermal management is essential in microelectronics to prevent overheating and maintain performance. This study investigates a double-layered sinusoidal microchannel heat sink with porous fins (PMHS), using water as the coolant, to enhance microscale heat transfer. Through computational fluid dynamics (CFD) simulations, the effects of porosity (ε = 0.66) and inlet velocity (0.2469–0.9665 m/s) on thermal and fluid dynamics are analyzed. The microchannel has specific dimensions and is subjected to a heat flux of 100 W/cm². Steady-state, incompressible, and laminar flow conditions are assumed, and porous fins are modeled with the Darcy-Forchheimer-Brinkman equation, accounting for permeability and drag effects. Results show a 1.5-fold increase in the heat transfer coefficient in porous zones compared to non-porous designs. Additionally, pressure drops are reduced with increasing porosity and maintain linear behavior with varying inlet velocities. The thermal resistance is also lowered, indicating improved heat dissipation. Velocity and temperature contours demonstrate enhanced fluid-solid interactions in porous fins. A mesh independence test confirms 4 million elements provide accurate results efficiently. Simulation results match experimental data with a maximum error of 4.79%, validating the methodology. Overall, the PMHS design significantly improves heat transfer while minimizing pressure loss and thermal resistance, outperforming traditional solid fin structures. This highlights the potential of porous media in optimizing thermal management in compact, high-performance systems. Future studies should examine different porosities and working fluids to further refine and expand the applicability of this innovative cooling approach.