We present a genome assembly from an individual male Plebejus argus (silver-studded blue; Arthropoda; Insecta; Lepidoptera; Lycaenidae). The genome sequence is 382 megabases in span. The entire assembly (100\%) is scaffolded into 23 chromosomal pseudomolecules with the Z sex chromosome assembled. The complete mitochondrial genome was also assembled and is 27.4 kilobases in length. Gene annotation of this assembly on Ensembl identified 12,693 protein coding genes.