Manganese-based oxides are one of the most promising high-performance supercapacitor (SC) electrode materials. In this work, a stable MnOx nanowires@MnOx nanosheets core–shell heterostructure electrode material consisting of MnOx nanosheets grown uniformly on the surface of MnOx nanowires has been prepared by a simple liquid phase method followed by thermal treatment. The electrode displays a specific capacity of 336 F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text] and exhibits a good cycling life of 83% capacitance retention after 5000 cycles. This is mainly due to the synergy effect between the one-dimensional MnOx nanowires as the backbone structure and the two-dimensional MnOx nanosheets with large specific surface area provide more active sites and the rapid transmission of electrons.