Protecting quantum batteries from environmental noise remains a challenge. Using exact Burshtein–Kubo equations, we study a two-spin quantum battery with Dzyaloshinskii–Moriya (DM) coupling under independent local longitudinal random telegraph noise (RTN). At a fixed effective noise scale, the DM-assisted slow-switching protocol yields a superadditive transient ergotropy gain and near-maximal ergotropy during the initial charging stage, while the no-DM slow-switching control reaches comparable ergotropy only in a later revival. A finite superadditive region persists at fixed RTN amplitude, with protocol-dependent location and gain. In the Ising model, the enhancement is nonmonotonic in DM strength, with intermediate coupling giving near-optimal performance. Dressed-channel analysis associates this enhancement with changes in transition frequencies and longitudinal-noise matrix elements that reduce slow-RTN spectral weight. Superadditivity also persists in the tested anisotropic XY model.