[en] Compared to their parent materials, oxygen vacancy (V${}_O$)–ordered phases of complex oxides exhibit distinct physical properties and show great potential in multifunctional devices. With the expected unique behaviors, however, most of the V${}_O$‐ordered oxide films are extremely difficult to synthesize due to their thermodynamic instabilities. Herein, using LaCoO${}_x$ as an example, the synthesis of large‐scale monophased V${}_O$‐ordered LaCoO${}_{2.67}$ and LaCoO${}_{2.5}$ films is realized by annealing as‐grown perovskite LaCoO${}_3$ films in vacuum with a special heating method. Their macroscopic properties, including the magnetic and electric transport and optical properties, are measured. It is demonstrated that the functionalities of LaCoO${}_x$ films can be manipulated by tuning the concentration and ordering of the V${}_O$. The method in this work can be applied to fabricate a wide range of V${}_O$‐ordered oxide films. (© 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)