The separation of electron–hole pairs has a significant influence on the photocatalytic process on semiconductors. In this work, BiOCl nanosheets with oxygen vacancies (BiOCl-OVs) have been prepared by reconstructing small hydrophobic BiOCl nanosheets. The transient photoresponse and the electron spin resonance (ESR) results prove that the separation of the charge carriers can be promoted by the oxygen vacancies via trapping the photoexcited electrons. Because of the improved charge separation and wide absorption of the solar spectrum, more photogenerated charge carriers are produced, as confirmed by the photocurrent response and the ESR measurements of the reactive oxygen species ^•O₂^– and ^•OH. Consequently, BiOCl-OVs present enhanced photocatalytic properties toward NO removal. Our study illustrates the importance of the construction of vacancies for improving photocatalytic performance.