Display omitted •Hierarchical NiMn-LDH nanosheets with well-aligned and highly oriented are successfully grown on Ni foam.•Rapid, ease of operation and tunable strategy: urea hydrolysis method.•High specific capacitance: 1511.1Fg−1 at 2.5Ag−1, 0.67Fcm−2 at 3mAcm−2.•Excellent rate capability: 80.1% retention at 48Ag−1; good cyclic stability: capacitance retention 92.8% after 3000 cycling. Well-aligned hierarchical NiMn-layered double hydroxide (NiMn-LDH) nanosheets are successfully grown on Ni foam by a facile one-step wet-method, wherein urea hydrolysis supplies alkali and carbonate ion. As-obtained NiMn-LDH@Ni foam presents highly oriented layered structure with ultrathin nanosheets. By fine tuning Ni/Mn mole ratio, the optimized Ni3Mn1-LDH@Ni foam displays maximum specific capacitance (1511Fg−1 at 2.5Ag−1), excellent rate capability (80.1% retention at 48Ag−1), high coulombic efficiency and long-term cycling life. In principle, this work provides a rapid and tunable strategy approach for synthesis of NiMn-LDH with largely enhanced supercapacitor behavior.