We present a genome assembly from an individual male Polyommatus icarus (the Common Blue; Arthropoda; Insecta; Lepidoptera; Lycaenidae). The genome sequence is 512 megabases in span. Most of the assembly is scaffolded into 23 chromosomal pseudomolecules, including the assembled Z chromosome. The mitochondrial genome has also been assembled and is 15.6 kilobases long. Gene annotation of this assembly on Ensembl identified 13,350 protein-coding genes.