Abstract: Martensitic stainless steels generally suffer from a trade-off between strength and ductility due to coarse precipitates and twin martensite, and conventional hot forging has proven inadequate to resolve this conflict. In this work, a high-nitrogen martensitic stainless steel (HNMSS) was processed by warm rolling at 600 ℃, and the resultant microstructure evolution and tensile properties were systematically investigated. The warm-rolled (WR) steel exhibits a fine-grained structure (prior austenite grain size: 2.9 μm) with high-density dislocations (4.50 × 1015 m−2), along with a reduced twin martensite content (6.5 vol.%), thinner twins (8.7 nm) and finer laths (59.5 nm), attributed to multipass rolling and precipitate pinning. Compared to the non-warm-rolled (NWR) steel, the WR steel achieved superior tensile strength (2311.0 MPa) and elongation (9.1%), representing increases of ~6.9% and ~62.5%, respectively, while maintaining excellent corrosion resistance (pitting potential: 299.6 mVSCE). Quantitative strengthening analysis reveals that dislocation multiplication strengthening is more pronounced in the WR steel (416 MPa), whereas twinning shear strengthening dominates in the NWR steel (245 MPa) after deformation. Furthermore, the WR steel exhibited finer dimples, a higher dimple fraction and a greater reduction in area, confirming enhanced matrix plasticity. These improvements stem from the competitive dislocation-twin relationship that promotes greater grain deformation in the WR steel. Overall, warm rolling provides an effective route to synergistically enhance the strength, ductility and corrosion resistance of HNMSSs.