Electrochemical conversion reaction, usually featured by multiple redox processes and high specific capacity, holds great promise in developing high-energy rechargeable battery technologies. However, the complete structural change accompanies by spontaneous atomic migration and volume variation during the charge/discharge cycle leads to electrode disintegration and performance degradation, therefore severely restrict the application of conventional conversion-type electrodes. Herein, we propose latticed-confined conversion chemistry, where the “intercalation-like” redox behaviour is realized on the electrode with a “conversion-like” high capacity. By delicately formulating the high-entropy compounds, the pristine crystal structure can be preserved well by the inert lattice framework, thus enabling an ultra-high initial Coulombic efficiency of 92.5% and a long cycling lifespan over thousand cycles after quasistatic charge-discharge cycle. This lattice-confined conversion chemistry unfolds ubiquitous insights into the localized redox reaction and sheds new lights on developing high-performance electrodes toward next-generation high-energy rechargeable batteries.