<p>The increasing demand for flexible displays and wearable electronics has driven extensive efforts to develop stretchable organic light-emitting diodes (OLEDs). A critical challenge in this field is the creation of emissive layers that combine high efficiency with mechanical robustness. Thermally activated delayed fluorescence (TADF) materials have attracted significant attention as third-generation emitters capable of achieving 100% internal quantum efficiency; however, their application in stretchable OLEDs has been limited. In this study, we propose an elastomer doping strategy. Polyurethane (PU) is incorporated into TADF polymers to improve their mechanical flexibility while maintaining a high luminescent efficiency. The resulting composite films exhibited excellent TADF characteristics and remarkable stretchability (75%). OLEDs fabricated from these materials achieved a maximum external quantum efficiency (EQE) of 14.26% and a peak luminance of 73570 cd·m⁻², with the PU-doped devices showing a significantly suppressed efficiency roll-off. Additionally, a fully stretchable OLED architecture was designed and operated under tensile strain to maintain stable electroluminescent performance. These results demonstrate that elastomer doping is an effective strategy for balancing the mechanical compliance with optoelectronic performance, offering a promising pathway for the development of high-performance stretchable OLEDs for flexible electronics.</p>