The current estimated population is 27,700.
In the 1930s Polish military authorities constructed a number of fortifications in the area of Sarny, known as Sarny Fortified Area (Sarnenski Rejon Umocniony), along the Sluch river. On September 17, 1939, following the Soviet attack on Poland (see: Polish September Campaign), the Sarny Fortified Area, defended by a small number of soldiers of the Border Defence Corps, was attacked by the Soviet 60th Rifle Division. The Poles, under Sergeant Jan Bolbot, defended the area for three days, despite Soviet crushing advantage. Bolbot was later awarded the Virtuti Militari.
In June of 1941, Sarny was captured by Nazi Germany, and again reclaimed by Soviet forces in 1944. Since 1939, it has been a part of Ukrainian SSR and later independent Ukraine.