Infrared stealth at elevated temperatures presents a significant challenge, as it necessitates the simultaneous suppression of thermal radiation and adaptive camouflage against diverse environmental backgrounds. However, existing systems often address only one aspect, failing to achieve high-temperature stealth across varying environments. To overcome this, a novel sandwich-structured composite is developed herein, which synergistically combines passive thermal management with active emissivity regulation. This integrated system comprises a directionally porous polyimide aerogel with ultralow thermal conductivity (29.7 mW m−1 K−1) as the foundational insulating layer, a polyimide/polyethylene glycol phase-change composite with high latent heat capacity (157.4 J g−1) as the intermediate thermal buffer, and an electrochromic device capable of dynamically modulating its infrared emissivity (emissivity contrast Δε = 0.69 across 2.5–14 µm bands) via reversible copper electrodeposition as the functional top layer. The composite demonstrates exceptional performance, including a maximum service temperature of up to 300°C and the ability to maintain a radiation temperature as low as 26.2°C on a 200°C hot background. Furthermore, its emissivity can be actively tuned to conform to varying surrounding conditions. This work provides a viable and advanced strategy for the development of intelligent, environment-adaptive thermal management systems for effective infrared camouflage in demanding and variable scenarios.