We present a genome assembly from an individual Nematostella vectensis (the starlet sea anemone; Cnidaria; Anthozoa; Actiniaria; Edwardsiidae). The genome sequence is 269.4 megabases in span. Most of the assembly is scaffolded into 15 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.4 kilobases in length.