[3] Until 1566 Unter- and Oberkulm formed a tithe district (German: Zehntbezirk), though their political separation was probably earlier.

In the 12th and 13th centuries the area was ruled by the Lenzburg family, then the Kyburgs and finally the Habsburgs.

By 1300 parts of the village were also owned by the monasteries of Schänis, Beromünster and Engelberg as well as local aristocratic families and the Dukes of Austria.

In the 14th and 15th centuries the Knights Hospitaller houses at Klingnau and Biberstein, and the collegiate church at Zofingen also became landholders in Unterkulm.

[3] After the conquest by Bern in 1415, Unterkulm remained part of the Court on Kulm in the District (German: Oberamt) of Lenzburg until 1798.

Towards the middle of the 18th century, in addition to agriculture, cotton spinning and weaving began in the Unterkulm.

Starting around 1800 the traditional three-field agriculture began to decline, though the dairy industry replaced crop production.

Of the rest of the land, 1.26 square kilometers (0.49 sq mi) or 14.2% is settled (buildings or roads), 0.02 km2 (4.9 acres) or 0.2% is either rivers or lakes.

37.9% of the total land area is heavily forested and 1.3% is covered with orchards or small clusters of trees.

The blazon of the municipal coat of arms is Tierced per fess Sable Argent and Azure.

[8] The age distribution, as of 2008[update], in Unterkulm is; 270 children or 9.3% of the population are between 0 and 9 years old and 407 teenagers or 14.0% are between 10 and 19.

[10] The historical population is given in the following table:[3] The Reformed Church on Hauptstrasse is listed as a Swiss heritage site of national significance.