The effect of Sb2O3 doping on Tc and Jc behavior of the polycrystalline YBa2Cu3O7−δ superconductor has been studied. While the overall Jc remained relatively low, the addition of a small amount of Sb2O3 (e.g., 0.5 wt %) noticeably improved transport Jc at 77 K by a factor of ∼6 at H=0 and of ∼80 at H=200 Oe. The magnetization hysteresis (ΔM) at H=0.9 T also increased by a factor of ∼3. The Jc improvement, which occurs in spite of the increased porosity, reduced grain size, and slightly suppressed Tc in the Sb2O3‐doped samples, is attributed to the stronger coupling at grain boundaries in view of the significantly reduced field dependence of transport Jc. Another beneficial effect of the Sb2O3 doping, i.e., accelerated kinetics of oxygen absorption during the tetragonal‐orthorhombic transformation, is also discussed. The Sb2O3 doping, if properly optimized, may be useful for alleviating both the grain boundary weak‐link behavior and the oxygen‐supply problem typically present in thick, dense, or metal‐clad YBa2Cu3O7−δ superconductors.