We present a genome assembly from an individual male Phragmatobia fuliginosa (the Ruby Tiger; Arthropoda; Insecta; Lepidoptera; Erebidae). The genome sequence is 629.4 megabases in span. Most of the assembly is scaffolded into 28 chromosomal pseudomolecules, including the assembled Z sex chromosome. The mitochondrial genome has also been assembled and is 15.4 kilobases in length. Gene annotation of this assembly on Ensembl identified 13,338 protein coding genes.