The present municipality was created in 1992, when Nyköping Municipality (of which it had been a part since 1974) was split up.
It is in the middle of the cultural Södermanland province. Although it only has around 10,000 permanent inhabitants, the population increases substantially in the summer due to the many summer houses.
Industry-wise, Gnesta mostly has small companies with few employed. There are about 800 registered companies in the municipality, and a "large" company would have 25-50 employees.