East Deer Township has three land borders, including Frazer to the north, south and west, Tarentum to the northeast, and a very small border with Springdale Township to the south-southeast along the Allegheny River.

Across the river in Westmoreland County, East Deer runs adjacent with Arnold.

At the 2000 census, there were 1,362 people, 606 households, and 350 families living in the township.

There were 682 housing units at an average density of 295.6 per square mile (114.1/km2).

37.1% of households were made up of individuals, and 16.5% were one person aged 65 or older.