Multivalent-ion (such as Zn²⁺, Mg²⁺, Al³⁺) batteries are considered as a prospective alternative for large-scale energy storage. However, the main problem of cathode materials for multivalent-ion batteries is the sluggish diffusion of multivalent ions. Many cathode materials will self-adjust under electrochemical conditions to achieve the optimal state for multivalent-ion storage. In this review, the significant role of electrochemical in situ structural reconstruction of cathode materials is suggested. The types, basic characteristics, and formation mechanisms of reconstructed phases have been systematically discussed and commented. The most important insight we pointed out is that the cathode materials with loose structures after in situ electrochemical activation are conducive to the reversible diffusion of multivalent ions. Moreover, several crucial issues of electrochemical activation and reconstruction were further analyzed and discussed. The challenges and future perspectives are presented in the final section.