RNA editing is the process of modifying RNA molecules by inserting, deleting, or substituting nucleotides. In flowering plants, RNA editing occurs predominantly in RNAs encoded by the organellar genomes of mitochondria and chloroplasts, and the main type of editing involves the substitution of cytidine with uridine at specific sites. Abnormal RNA editing in plants can affect gene expression, organelle function, plant growth, and reproduction. In this study, we report that ATPC1, the gamma subunit of ATP synthase inArabidopsischloroplasts, has an unexpected role in the regulation of editing at multiple sites of plastid RNAs. The loss of function ofATPC1severely arrests chloroplast development, causing a pale-green phenotype and early seedling lethality. Disruption ofATPC1increases the editing ofmatK-640,rps12-i-58,atpH-3′UTR-13210, andycf2-as-91535 sites while decreasing the editing ofrpl23-89,rpoA-200,rpoC1-488, andndhD-2 sites. We further show that ATPC1 participates in RNA editing by interacting with known multiple-site chloroplast RNA editing factors, including MORFs, ORRM1, and OZ1. The transcriptome in theatpc1mutant is profoundly affected, with a pattern of defective expression of chloroplast development-related genes. These results reveal that the ATP synthase γ subunit ATPC1 is involved in multiple-site RNA editing inArabidopsischloroplasts.