The rose-grain aphid Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) is one of the most important aphid pests for cereals worldwide. Some studies have examined the biological and ecological characteristics of M. dirhodum. However, the lack of genomic data limits in-depth studies of this organism. Here, we present a chromosome-level genome assembly of M. dirhodum using PacBio long HiFi reads and Hi-C technology. The final genome assembly is 447.8 Mb, with 98.50% of the assembled sequences anchored to nine chromosomes. The contig and scaffold N50 values are 7.82 Mb and 37.54 Mb, respectively. A total of 18,003 protein-coding genes were predicted, of which 92.05% were functionally annotated. Comparative transcriptomic analyses identified a number of genes that might be related to wing dimorphism, including the insulin receptor, insulin receptor substrate, forkhead box protein O (Foxo), and ecdysone receptor. These results may provide an important reference for understanding the ecology, genetics, and evolution of this organism or even other aphid insects.