Abstract Sustainable thermal management of high-heat-flux electronics beyond Moore’s Law requires micro thermoelectric coolers (μ-TECs) that are both high-performance and environmentally sustainable. However, state-of-the-art μ-TECs rely on Bi2Te3-based materials, whose tellurium scarcity, toxicity concerns and limited mechanical robustness hinder widespread adoption. Mg-based thermoelectric materials offer a promising alternative but remain challenging to integrate into microscale devices.