To address the growing threat of high-energy laser (HEL) attacks, this study focuses on developing phenolic resin-based composite coatings reinforced with various metallic and ceramic fillers. Among the formulations tested, the aluminum–molybdenum diboride (Al + MoB2) composite coating exhibited the most promising laser ablation resistance. While pure aluminum displayed the highest reflectivity and alumina the lowest, the introduction of MoB2 into the aluminum matrix significantly reduced reflectivity without compromising thermal performance. The Al + MoB2 coating demonstrated the lowest backside temperature rise and minimal weight loss during laser exposure, indicating excellent thermal barrier characteristics and high resistance to material degradation. This superior performance is attributed to the high thermal stability and char-forming capability of MoB2, which helps dissipate energy effectively while maintaining structural integrity. In contrast, the pure alumina coating, despite its low reflectivity, resulted in a higher backside temperature—likely due to its higher thermal conductivity and direct energy transfer. Overall, the Al + MoB2 composite offers a favorable combination of reflectance control, thermal insulation, and durability, positioning it as a strong candidate for protective coatings against HEL threats in defense and aerospace applications.