Jász-Nagykun-Szolnok was an administrative county (comitatus) in the Kingdom of Hungary.

Its territory, which is now in central Hungary, was slightly smaller than that of present Jász-Nagykun-Szolnok county.

Jász-Nagykun-Szolnok county was formed in 1876 from the territories of the Külső-Szolnok part of Heves-Külső-Szolnok County, the Jászság (Jazygia) and the Nagykunság (great Cumania).

The term Jász originates from the Jassic people (cf.

Alans) who moved to this area of Hungary from the Pontic steppes sometime in the 13th century.