The pursuit of anode materials capable of rapid and reversible potassium storage performance is a challenging yet fascinating target. Herein, a heterointerface engineering strategy is proposed to prepare a novel superstructure composed of amorphous/crystalline ReTe anchored on MXene substrate (A/C-ReTe/MXene) as an advanced anode for potassium-ion batteries (KIBs). The A/C-ReTe/MXene anode exhibits outstanding reversible capacity (350.4 mAh g after 200 cycles at 0.2 A g), excellent rate capability (162.5 mAh g at 20 A g), remarkable long-term cycling capability (186.1 mAh g at 5 A g over 5000 cycles), and reliable operation in flexible full KIBs, outperforming state-of-the-art metal chalcogenides-based devices. Experimental and theoretical investigations attribute this high performance to the synergistic effect of the A/C-ReTe with a built-in electric field and the elastic MXene, enabling improved pseudocapacitive contribution, accelerated charge transfer behavior, and high K ion adsorption/diffusion ability. Meanwhile, a combination of intercalation and conversion reactions mechanism is observed within A/C-ReTe/MXene. This work offers a new approach for developing metal tellurides- and MXene-based anodes for achieving stable cyclability and fast-charging KIBs.