It has land borders with the counties of Kalmar to the southeast, Jönköping to the southwest, Örebro to the northwest, and Södermanland to the northeast.

Östergötland County has a population of 456,550 (September 30, 2017) and the capital and biggest city is Linköping.

Linköping and neighbouring twin city Norrköping together form one of Sweden's metropolitan areas; The Linköping-Norrköping Corridor is therefore sometimes marketed as The Fourth Metropolitan Region of Sweden,[citation needed] the other three being Stockholm, Gothenburg and Malmö.

The County Administrative Board is a Government Agency headed by a Governor.

The table details all Riksdag election results of Östergötland County since the unicameral era began in 1970.