We present a genome assembly from an individual female Spilarctia lutea (the Buff Ermine; Arthropoda; Insecta; Lepidoptera; Erebidae). The genome sequence is 584.8 megabases in span. Most of the assembly is scaffolded into 32 chromosomal pseudomolecules, including the assembled Z and W sex chromosomes. The mitochondrial genome has also been assembled and is 15.4 kilobases in length. Gene annotation of this assembly on Ensembl identified 18,304 protein coding genes.