The electrochemical performance of MnO is limited by its low surface area, sluggish kinetics, and poor stability. Herein, hollow MnO nanoboxes (H-MnO-TEA) are successfully prepared using Prussian blue analogs (KMn[FeCN], Mn-PBA) via a facile triethanolamine-induced strategy to tackle the abovementioned hurdles. Mn-PBA not only acts as a self-sacrificial template, but also triggers the “self-redox reaction” to in-situ form MnO, in which the dissociated [FeCN] oxidates Mn in the alkalic medium. Besides, triethanolamine is employed as an intermediate modulator to induce the formation of hollow MnO and adjust the coordination environment of H-MnO-TEA. Experimental results and DFT calculations demonstrate that abundant active Mn and oxygen vacancies in H-MnO-TEA are beneficial to providing more active sites, improving electrical conductivity, and boosting Na diffusion kinetics. Based on the improved structural and electrical properties, H-MnO-TEA delivers a high specific capacitance of 316.8 F g at 0.5 A g, superior rate performance, and excellent capacitive retention of 96.1 % after 10,000 cycles. This work provides an efficient way to construct hollow metal oxides for high-performance energy storage devices along with their underlying mechanism.