The advancement of multispectral surveillance technologies has rendered conventional single-band camouflage materials ineffective, driving an urgent demand for multispectral-compatible stealth materials. Herein, we report a multidimensional MXene-based composite aerogel engineered via cost-effective lyophilization for radar-infrared compatible camouflage. As building blocks, few-layer Ti3C2Tx MXene nanosheets functionalized with NiB alloy nanoparticles and thermoresponsive VO2 phase-change materials are cross-linked by poly(vinyl alcohol) to construct the MXene/NiB/VO2 composite aerogel through one-step cryo-assembly. The composite demonstrates a remarkable multispectral stealth performance. The thermal radiation temperature of a heated target is reduced from 180 to 55 °C. In addition, a minimum reflection loss (RLmin) of -54.7 dB with an effective absorption bandwidth of 7.1 GHz (8.8-15.9 GHz) at an ultralow low density of 19 mg·cm-3 has been achieved. These breakthroughs stem from synergistic mechanisms: low infrared emissivity, suppressed thermal conduction, dynamic temperature regulation via the VO2 phase transition, and multimodal electromagnetic dissipation. This work establishes a material design paradigm to reconcile infrared-microwave spectral incompatibilities through multidimensional heterostructure engineering, providing a roadmap for next-generation adaptive multispectral stealth technologies.