ABSTRACT In this work, we revisit the size–luminosity relation of the extended narrow line regions (ENLRs) using a large sample of nearby active galactic nuclei (AGNs) from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The ENLRs ionized by the AGN are identified through the spatially resolved BPT diagram, which results in a sample of 152 AGN. By combining our AGN with the literature high-luminosity quasars, we found a tight log-linear relation between the size of the ENLR and the AGN $\rm O\, III$λ5007 Å luminosity over four orders of magnitude of the $\rm O\, III$ luminosity. The slope of this relation is 0.42 ± 0.02 which can be explained in terms of a distribution of clouds photoionized by the AGN. This relation also indicates that the AGNs have the potential to ionize and heat the gas clouds at a large distance from the nuclei without the aids of outflows and jets for the low-luminosity Seyferts.†