The origins of the only free royal town in the historical garrison county of Vas (Eisenburg) go back to the third quarter of the thirteenth century.

Sometime before 1274 Henry I and his son Ivan moved the court of the Kőszegi, a breakaway branch of the family, from Güssing to Kőszeg (Güns).

Only in 1327 did Charles Robert of Anjou finally break the power of the Kőszegi family in Western Transdanubia, and a year later, in (1328), elevated the town to royal status.

In 1392 the royal town became a fiefdom, when the Palatinate Nicolas Garai repaid a bond paid to King Sigismund of Luxembourg by the Ellerbach family from Monyorókerék.

After the Turkish wars, in 1695 the garrison and surrounding areas of Kőszeg fell into the hands of the Esterházy dukes, where it remained until 1931.

Along with Szombathely, Kőszeg was the most important fortress for the kuruc military leadership from 1705–1708, to liberate and hold onto the areas west of the Rába.

Only a few workshops survived the production crisis within the guild system during the Hungarian reformation of the early nineteenth century.

The International Baccalaureate (IB) program, which most English-speaking students at the school follow, was created at the Grande Boissière campus.

[6] When the Red Army approached Kőszeg in March, 1945, the Hungarian commander, Béla Király, surrendered the city to spare it further destruction.

The financially feeble town is looking at options for renewal through an injection of capital from outside investors and is seeking support from government agencies and the European Union.

After the Second World War officially, 117 Germans were expelled,[9] but in fact more German-speaking people were deported because the town's population declined from 10,320 (in 1941) to 8,780 (in 1949).