The main population centre and administrative center is the village of Åmli which lies along the river Nidelva.

The official blazon is "Azure, a beaver rampant regardant argent" (Norwegian: På blå grunn ein oppreist sølv bever med hovudet vendt bakover).

The beaver has a tincture of argent which means it is commonly colored white or gray, but if it is made out of metal, then silver is used.

It is part of the Aust-Nedenes prosti (deanery) in the Diocese of Agder og Telemark.

Several uninhabited areas (the Espestøl, Reinefoss, and Espestølstykket farms) were transferred to Nissedal municipality in Telemark county on 1 January 1965.

The most densely populated area is around the municipal center of Åmli, which lies on the banks of the river Nidelva.

In the southern part of the municipality the Sørlandsbanen railway line passes through the area, stopping at the Nelaug Station.

The largest villages in Åmli include Dølemo, Nelaug, Hillestad, and Askland.

The Åmli hills are wooded and typically range from 700 to 800 metres (2,300 to 2,600 ft) above sea level.

At 930 metres (3,050 ft), the highest point is Trongedalsfjell, which lies between the Tovdal and Gjøvdal valleys.

The municipal council (Kommunestyre) of Åmli is made up of 17 representatives that are elected to four-year terms.

Agriculture, including sheep husbandry, provides a minor contribution to the economy.

Electrical power is generated by a hydroelectric plant at Flatefoss, which regulates the level of the lake, Nelaug.