AbstractElemental defect in transition metal oxides is an important and intriguing subject that result in modifications in variety of physical properties including atomic and electronic structure, optical and magnetic properties. Understanding the formation of elemental vacancies and their influence on different physical properties is essential in studying the complex oxide thin films. In this study, we investigated the physical properties of epitaxial SrRuO₃ thin films by systematically manipulating cation and/or oxygen vacancies, via changing the oxygen partial pressure (P(O₂)) during the pulsed laser epitaxy (PLE) growth. Ru vacancies in the low-P(O₂)-grown SrRuO₃ thin films induce lattice expansion with the suppression of the ferromagnetic T_C down to ~120 K. Sr vacancies also disturb the ferromagnetic ordering, even though Sr is not a magnetic element. Our results indicate that both A and B cation vacancies in an ABO₃ perovskite can be systematically engineered via PLE, and the structural, electrical, and magnetic properties can be tailored accordingly.