Affoltern am Albis (abbreviated as Affoltern a.A.; Swiss German: Affoltere) is a town and a municipality in the district of Affoltern in the canton of Zürich in Switzerland .

Affoltern is first mentioned in 1190 as Afiltre.

Affoltern has an area of 10.6 km2 (4.1 sq mi). Of this area, 45.7% is used for agricultural purposes, while 28.9% is forested. Of the rest of the land, 25% is settled (buildings or roads) and the remainder (0.5%) is non-productive (rivers, glaciers, or mountains).

The municipality is located west of the Albis hills in the moraine landscape around the Reuss.