We present a genome assembly from an individual maleCybosia mesomella(the Four-dotted Footman; Arthropoda; Insecta; Lepidoptera; Erebidae). The genome sequence is 948 megabases in span. Most of the assembly is scaffolded into 31 chromosomal pseudomolecules, with the Z sex chromosome assembled. The mitochondrial genome has also been assembled and is 15.4 kilobases in length.