<p>Bifunctional materials with high heat conduction and strong microwave absorption play a pivotal role in addressing the challenges of heat accumulation and signal crosstalk in modern devices. However, the design of such bifunctional materials is constrained by the incompatibility between thermal conductivity and microwave absorption. We tackle this challenge by employing a hydrothermal-microwave-assisted solvothermal method to construct Te@Cu_xTe_1−x core-shell nanofibers (CSNFs) via a Cu-doping strategy. The multi-heterointerfaces of Te/CuTe, CuTe/Cu_2.74Te₂, and Cu_2.74Te₂/Cu₇Te₄ in the CSNFs were controlled by adjusting the feeding ratio (<i>β</i> = Cu²⁺/Te) to simultaneously enhance their thermal conduction and microwave absorption. Through Cu doping, a low work function (W_f) was achieved to attain high <i>σ</i> and Ohmic loss (<InlineEquation ID="IEq1"><EquationSource Format="TEX">\(\:{\epsilon\:}_{c}^{{\prime\:}{\prime\:}}\)</EquationSource></InlineEquation>). Besides, Te@Cu_xTe_1−x multi-heterojunctions were formed to enhance interfacial polarization, and the active phonon frequency was extended with good phonon matching to improve thermal conduction. With 1.7&#xa0;mm in thickness and 30 wt% in load, the CSNFs formed at <i>β</i> = 0.250 achieved a wide band (3.444&#xa0;GHz/mm), strong absorption (-36.82 dB), and low RCS reduction (36 dB m²), indicating their excellent near-field EM protection and far-field Radar wave stealth performance. Moreover, the Te@Cu_xTe_1−x/TPU membrane exhibited high heat conductance (3.95&#xa0;W/(m K)) under a small load (15 wt%), along with high strength (39.77&#xa0;MPa) and good flexibility (elongation: 873%). Our research results demonstrate the great application potential of Te@Cu_xTe_1−x CSNFs in the EM protecting and heat managing fields, providing theoretical guidance for further design of tellurium-based alloys as integrated materials with effective microwave absorption and thermal conduction.</p> Graphical abstract <p></p>