<p>Efficient thermal management is essential in modern electronic devices due to increasing power densities and miniaturization trends, which lead to significant heat generation in confined spaces. This study presents a comprehensive design characterization of pin-fin heat sinks by integrating Computational Fluid Dynamics (CFD) simulations with precision Additive Manufacturing (AM) for rapid prototyping and experimental validation. Various pin-fin geometries were designed and analyzed using CFD to evaluate their thermal and flow behavior under different conditions. The simulations employed the standard k–ε turbulence model, which demonstrated the best agreement with experimental data obtained from controlled wind-tunnel testing. Results revealed that heat sinks with triangular pin fins exhibited superior thermal performance compared to rectangular and circular designs. This superiority is reflected by lower average temperatures and higher Nusselt numbers, indicating more efficient heat transfer and enhanced heat dissipation. The triangular geometry also promoted airflow patterns that improved fluid mixing and increased the contact time between the cooling air and heat-sink surfaces. The study also investigated the effect of hollow-core fins, showing that only the hollow circular design enhanced convection due to its smooth internal flow path, whereas sharp-edged hollow rectangular and triangular fins hindered airflow and reduced efficiency. The measured performance of the 3D-printed LPBF prototypes showed excellent agreement with CFD predictions, confirming the reliability of the integrated experimental–numerical approach. While no direct design optimization was conducted, the validated CFD-AM framework established here provides a robust foundation for future optimization and design improvement of heat-sink geometries in high-performance electronic applications.</p>