Prunus campanulata is an important flowering cherry germplasm of high ornamental value. Given its early-flowering phenotypes, P. campanulata could be used for molecular breeding of ornamental species and fruit crops belonging to the subgenus Cerasus. Here, we report a chromosome-scale assembly of P. campanulata with a genome size of 282.6 Mb and a contig N50 length of 12.04 Mb. The genome contained 24,861 protein-coding genes, of which 24,749 genes (99.5%) were functionally annotated, and 148.20 Mb (52.4%) of the assembled sequences are repetitive sequences. A combination of genomic and population genomic analyses revealed a number of genes under positive selection or accelerated molecular evolution in P. campanulata. Our study provides a reliable genome resource, and lays a solid foundation for genetic improvement of flowering cherry germplasm.