<p>Thermal barrier coatings (TBCs) are widely used to protect metallic components in turbine engines operating at high temperatures. Traditionally, their performance has been optimized by minimizing thermal conductivity and maintaining phase stability. At very high temperatures, however, radiative heat transfer becomes a significant contributor to total heat flux, especially within the near-infrared (NIR) spectral range, and must be considered. Most conventional TBC materials are wide band gap insulators, rendering them transparent to the NIR radiation. This study investigates the electronic and optical properties of 16 transition metal-substituted tetragonal yttria-stabilized zirconia (t-YSZ) using first-principles many-body perturbation theory within the G₀W₀ and Bethe-Salpeter equation (BSE) framework. The findings indicate that substitutional transition metal cations with partially filled <i>d</i>-orbitals introduce localized electronic states within the host band gap, enabling <i>d</i> − <i>d</i> excitonic transitions below the gap edge while preserving the wide band gap required for thermal insulation. Analysis of electron-hole pair distributions identifies two primary categories of optically active excitons: charge-transfer excitons (Type-I and Type-I’) and defect-bound excitons (Type-II and Type-II’), each exhibiting distinct spatial localization and binding energies. The calculated NIR absorption characteristics are compiled into a Dieke design map that enables rapid evaluation of candidate transition metal substitutions for thermal radiation barrier coating applications.</p>