It is situated at an altitude of 517 m (1,696 ft) at the foot of the Vrancea Mountains, on the banks of the rivers Zagon and Păpăuți.

The locality formed part of the Székely Land region of the historical Transylvania province.

In August 1940, under the auspices of Nazi Germany, which imposed the Second Vienna Award, Hungary retook the territory of Northern Transylvania (which included Zagon) from Romania.

Towards the end of World War II, however, the commune was taken back from Hungarian and German troops by Romanian and Soviet forces in September 1944.

In 1950, after Communist Romania was established, Zagon became part of the Târgu Secuiesc Raion of Stalin Region.