Conjugated polymers (CPs) are promising materials for optical sensing, bioelectronics, and medical imaging due to their tunable photophysics and compatibility with flexible and biological systems. However, achieving (1) bright emission in the NIR-II/SWIR region and (2) material transience after application, remain as major challenges limiting widespread adoption. In this work, we present conjugated polymer nanoparticles (CPNs) that address both limitations. Unique CPNs exhibiting aggregation-enhanced emission (AEE) are introduced, demonstrating bright NIR/SWIR fluorescence upon nanoparticle formation. We further demonstrate that oxidative degradation, typically considered a failure pathway in organic electronics, can be harnessed to enable controlled nanoparticle transience. Together, these results establish molecular design principles linking optical performance, nanoparticle structure, and degradation behavior in luminescent conjugated polymer systems.