Its territory is now in central Hungary, comprising roughly the territory of the present Hungarian county Pest and the northern part of present Bács-Kiskun county.

The Pest-Pilis-Solt-Kiskun county shared borders with the counties Komárom, Esztergom, Hont, Nógrád, Heves, Jász-Nagykun-Szolnok, Csongrád, Bács-Bodrog, Tolna and Fejér.

A part of the county (Pilis) was on the west bank of the Danube, near Budapest.

The Solt region (the left bank of the Danube south of Ráckeve), which previously belonged to Fejér county, was incorporated into Pest-Pilis-Solt county in the 17th century.

After World War II, the county was split into two roughly equal parts.