We present a genome assembly from an individual female Aplocera efformata (the lesser treble-bar; Arthropoda; Insecta; Lepidoptera; Geometridae). The genome sequence is 349.5 megabases in span. Most of the assembly (99.97\%) is scaffolded into 32 chromosomal pseudomolecules, with W and Z sex chromosomes assembled. The complete mitochondrial genome was also assembled and is 15.4 kilobases in length.