Significantly improved flux pinning has been achieved in bulk YBa2Cu3O7−&dgr;superconductor (‘‘123’’ compound) containing fine‐scale defects (<∼50 A˚ thick). The measuredJcintragrain of ∼105A/cm2at 77 K,H=0.9 T is about ten times higher than the typical values for bulk Y‐Ba‐Cu‐O. The improved structure was produced by rapid decomposition at 920 °C of the YBa2Cu4O8(‘‘124’’) precursor. This new and simple processing route could lead to a commercially viable processing technique for flux‐pinning enhancement in bulk Y‐Ba‐Cu‐O.