Desmodesmus costato-granulatus (Skuja) Hegewald 2000 (Sphaeropleales, Chlorophyta) is a small, spineless green alga that is abundant in the freshwater phytoplankton of oligo- to eutrophic waters worldwide. It has a high lipid content and is considered for sustainable production of diverse compounds, including biofuels. Here, we report the draft whole-genome shotgun sequencing of D. costato-granulatus strain SAG 18.81. The final assembly comprises 48,879,637 bp with over 4,141 scaffolds. This whole-genome project is publicly available in the CNSA (https://db.cngb.org/cnsa/) of CNGBdb under the accession number CNP0000701.