Intrinsically stretchable organic light-emitting diodes (is-OLEDs), composed entirely of inherently stretchable functional layers, represent a promising enabling technology for wearable electronics due to stretching and deformation endurance during the dynamic movements of the human body. However, achieving high performance and stretchability is challenging due to limited ductility in conjugated emissive materials and the low quality of stretchable transparent electrodes (STEs). In this study, we explore an elastic-microphase-engineered emissive layer strategy for is-OLEDs. This involves investigating the effects of incorporating different styrene-butadiene-styrene block copolymer derivative elastomers into a green polyfluorene emissive polymer. The miscibility between elastomers and emissive polymers is found to be critical in regulating three-dimensional microphase separation in the blend, thus simultaneously affecting mechanical and optoelectronic properties. In addition, by pre-burying conductive polymer PH1000, the smoothed dual-embedded hybrid electrode PH1000@AgNWs@TPU (PAT) STE with superior conductivity, stretchability, and stability is achieved. As a result, the obtained is-OLED demonstrated a record luminance of 33,443 cd m−2 and stretchability up to 120%, while also maintaining approximately 90% of its initial luminance after 100 cycles of dynamic stretching at 15% strain, representing a significant stride towards realizing the full potential of is-OLEDs for next-generation wearable electronic applications. Elastic-microphase-engineering and dual-embedded electrodes enable intrinsically stretchable OLEDs with record brightness (33,443 cd/m²) and stretchability (120%).