Cation disordered rocksalt (DRX) materials are promising electrode alternatives for next-generation battery technology due to their superior performances concerning capacity and rate capability. These materials are usually prepared via heat treatment or mechanochemical synthesis. Recently, several cation DRX oxides with desirable cycling behaviours have been prepared through electrochemical lithiation of a series of binary metal oxides that have a non-fcc oxygen sublattice. Capitalising on these findings, we strategically investigated two Mn oxides with unique oxygen structures. Through an analysis combining X-ray diffraction and pair distribution function techniques, an electrochemically active cation DRX phase was identified in both oxides upon electrochemical lithiation. Jointly with the earlier reports, our new findings constitute empirical evidence pointing to a general principle that underpins the electrochemical DRX transformation, opening up new opportunities for the development of higher energy density batteries.