<p>High-entropy alloys, defined as single-phase solid solutions composed of five or more elements, have attracted considerable attention for their exceptional mechanical properties. However, their electronic and magnetic transport properties remain largely unexplored. In this study, we focus on the anomalous Nernst effect, a magnetic thermoelectric phenomenon, in FeCoNi-based ferromagnetic high-entropy alloy thin films at room temperature. We systematically examined the influence of heavy-element concentration in FeCoNiCuPd. Increasing the Pd content to 10, 20, and 30 at% led to the anomalous Nernst conductivity of 0.53, 0.61, and 0.74&#xa0;A m⁻¹ K⁻¹, respectively, attributable to the strong spin–orbit coupling of Pd. These results indicate that adding heavy elements effectively enhances transverse transport in high-entropy alloys. To further enhance the anomalous Nernst effect, we introduced an even heavier element, Pt, into the alloy. The resulting FeCoNiPdPt thin film exhibited a high anomalous Nernst conductivity of ~ 0.97&#xa0;A m⁻¹ K⁻¹ together with a large anomalous Nernst thermopower of ~ 0.9 µV K⁻¹, demonstrating the thermoelectric potential of these alloys.</p>