Abstract We successfully introduced high-density linear defects as artificial pinning centers (APCs) of the quantized vortices into YBCO films, during the film deposition procedure. APCs were introduced perpendicular to the film surface by using the distributed nanosized Y 2O 3 islands prepared on SrTiO 3(1 0 0) substrates. It is possible to induce strong changes on the shape and density of the Y 2O 3 islands by varying the deposition conditions. The highest Y 2O 3 islands density, 226/μm 2, was obtained with fifteen laser pulses at 800 °C of substrate temperature. Even if only 10% of the induced defects act as effective pinning centers, J c of YBCO film grown on the Y 2O 3 nanoislands/SrTiO 3 substrate increased to 1.8 × 10 7 A/cm 2 (20 K, B∥ c, 0 T), which is 1.5 times higher than that of the pure YBCO film.