We present a genome assembly from an individual male Diachrysia chrysitis (the Burnished Brass; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 386 megabases in span. Most of the assembly is scaffolded into 31 chromosomal pseudomolecules, including the assembled Z sex chromosome. The mitochondrial genome has also been assembled and is 15.3 kilobases in length. Gene annotation of this assembly on Ensembl identified 18,320 protein coding genes.