Developing highly efficient and robust electrocatalysts for oxygen evolution reaction (OER) is critical to renewable energy technologies. Here, we report an effective strategy to enhance the OER activity of a perovskite electrocatalyst through improving the electrical conductivity introduced by the structural transition. La 0.7Sr 0.3Fe 1−xNi xO 3−δ (denoted as LSFN-x) with increasing Ni content is found to crystallize in a higher symmetry structure and exhibit improved OER catalytic performance. The optimized cubic LSFN-0.4 catalyst delivers a 90–times higher specific activity than its non-doped parent rhombohedral compound La 0.7Sr 0.3FeO 3−δ at an overpotential of 340 mV, with an overpotential of only 320 mV for 10 mA cm −2 and a low Tafel slope of 35 mV dec −1 in 0.1 M KOH, while maintaining excellent durability during 1000 continuous cycles and 50 h-water-splitting in a laboratory-scale electrolyzer. The enhanced OER catalytic performance of LSFN-0.4 is highly correlated with its increased conductivity as well as the increased oxygen vacancy concentration.