SummaryPlant architecture is a key agronomical factor determining crop yield and has been a major target of cereal crop domestication. The transition of plant architecture from the prostrate tiller of typical African wild rice (Oryza barthii) to the erect tiller of African cultivated rice (Oryza glaberrima) was a key step during domestication of African rice. Here we show that PROG7 (PROSTRATE GROWTH 7), a zinc‐finger transcription factor gene on chromosome 7, is required for the prostrate growth of African wild rice. Mutations in the promoter region of prog7 reduced the level of gene expression in the tiller base, leading to erect growth in African cultivated rice. Sequence comparison and haplotype analysis show that 90 varieties of cultivated rice from 11 countries carry the same mutations in the prog7 region. A strong signal in a 60‐kb genomic region was detected around the prog7 gene, suggesting that the region was under strong positive selection during the domestication process. Identification of the PROG7 gene provides new insights into the molecular basis of plant architecture in crops and facilitates investigation of the history of domestication of African rice.