Bennwil is a municipality in the district of Waldenburg in the canton of Basel-Country in Switzerland.
Bennwil is first mentioned in 1218 as Bendewilere. A mention of the village that claimed to be from 1189 is believed to be a fake.
Bennwil has an area, , of . Of this area, or 53.3% is used for agricultural purposes, while or 40.9% is forested. Of the rest of the land, or 5.5% is settled (buildings or roads), or 0.5% is either rivers or lakes.
Of the built up area, housing and buildings made up 3.7% and transportation infrastructure made up 1.1%. Out of the forested land, 37.8% of the total land area is heavily forested and 3.1% is covered with orchards or small clusters of trees. Of the agricultural land, 18.0% is used for growing crops and 28.4% is pastures, while 5.2% is used for orchards or vine crops and 1.7% is used for alpine pastures. All the water in the municipality is flowing water.
The municipality is located in the Waldenburg district, in the Bennwilerbach or Walibach valley. It consists of the linear village of Bennwil and about 24 individual farm houses.
The blazon of the municipal coat of arms is Azure, a Paschal lamb Argent, hoofed and haloed Or, holding a flag Argent a Cross Gules.
Bennwil has a population () of . , 4.4% of the population are resident foreign nationals. Over the last 10 years (1997–2007) the population has changed at a rate of 2.5%.
Most of the population () speaks German (580 or 96.2%), with Serbo-Croatian being second most common (9 or 1.5%) and English being third (6 or 1.0%). There are 3 people who speak French.
the gender distribution of the population was 53.2% male and 46.8% female. The population was made up of 597 Swiss citizens (94.2% of the population), and 37 non-Swiss residents (5.8%) Of the population in the municipality 237 or about 39.3% were born in Bennwil and lived there in 2000. There were 179 or 29.7% who were born in the same canton, while 139 or 23.1% were born somewhere else in Switzerland, and 37 or 6.1% were born outside of Switzerland.