In 1921 the counties of Moson and Sopron were each divided in two, with their western districts together forming the northern half of the Austrian province of Burgenland.

Between 1921 and 1945, Győr and Moson became part of the "provisionally and administratively unified counties of Győr–Moson–Pozsony", renamed after 1945 as simply Győr-Moson.

In 1947 the borders of this county were modified when Hungary lost three villages in the far north of Győr–Moson to Czechoslovakia as a consequence of the Hungarian peace treaty signed in that year.

Though Győr is the capital, there is a strong rivalry between it and Sopron, historically an important cultural centre on its own right.

The county also contains Hegyeshalom, Hungary's busiest international land border crossing point.