The development of non-precious metal catalysts with excellent performance in the oxygen evolution reaction (OER) is crucial for large-scale and low-cost hydrogen production from water. FeCrNiCoTi multi-principal element alloy (MPEA), which is free of precious metals and possesses four specific effects, holds promise as a low-cost and efficient electrocatalyst for water electrolysis. However, further enhancing the exposure of its active sites remains a challenge. To address this issue, the FeCrNiCoTi MPEA powder was long-term mechanically milled to refine the grain size, introduce defects, and (oxygen) hydroxide species with the aim of improving OER catalytic performance. Such powder milled after 80 h exhibits an overpotential of 296 mV at 10 mA/cm2 and the Tafel slope of 41.3 mV/dec, with continuous stability for 40 h in 1.0 M KOH electrolyte, comparable to the commercial RuO2 catalyst. This work provides a simple, practical and effective approach for the preparation of high-performance, low-cost OER electrocatalysts.