The crystal structure of cabotegravir has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Cabotegravir crystallizes in space group P21212 (#18) with a = 31.4706(11), b = 13.4934(3), c = 8.43811(12) Å, V = 3,583.201(18) Å3, and Z = 8 at 298 K. The crystal structure consists of stacks of roughly parallel molecules along the c-axis. The molecules form layers parallel to the bc-plane. O–H···O hydrogen bonds link one of the two independent molecules into chains along the b-axis. The powder pattern has been submitted to the International Centre for Diffraction Data (ICDD®) for inclusion in the Powder Diffraction File™ (PDF®).