This study presents a multiphase engineering approach to create stretchable phosphorescent polymers, which are crucial for advanced wearable electronics. The researchers developed a block copolymer system that combines stiffness and softness, achieving an intrinsic stretchability of 712% while maintaining an ultralong phosphorescence lifetime of up to 981.11 ms. This is achieved through microphase separation, where the polyacrylic acid (PAA) hard phase provides a rigid environment for phosphorescence, while the poly (butyl methacrylate) (PBMA) soft phase enhances stretchability. The multiphase design is applicable to binary and ternary initiator systems, enabling color-tunable phosphorescence in the visible range. The stretchable copolymers exhibit excellent mechanical properties, optical transparency, and thermal stability, making them suitable for applications such as multi-level volumetric data encryption and stretchable multicolor afterglow displays. The work provides a fundamental understanding of nanostructures and material properties for designing stretchable materials and extends the potential of phosphorescence polymers.This study presents a multiphase engineering approach to create stretchable phosphorescent polymers, which are crucial for advanced wearable electronics. The researchers developed a block copolymer system that combines stiffness and softness, achieving an intrinsic stretchability of 712% while maintaining an ultralong phosphorescence lifetime of up to 981.11 ms. This is achieved through microphase separation, where the polyacrylic acid (PAA) hard phase provides a rigid environment for phosphorescence, while the poly (butyl methacrylate) (PBMA) soft phase enhances stretchability. The multiphase design is applicable to binary and ternary initiator systems, enabling color-tunable phosphorescence in the visible range. The stretchable copolymers exhibit excellent mechanical properties, optical transparency, and thermal stability, making them suitable for applications such as multi-level volumetric data encryption and stretchable multicolor afterglow displays. The work provides a fundamental understanding of nanostructures and material properties for designing stretchable materials and extends the potential of phosphorescence polymers.