Wilderswil has a population (as of December 2018) of 2,658.
 As of 2010, 10.0% of the population are resident foreign nationals.
In the period from 2000 to 2010, the population changed at a rate of 12.7%.
Migration accounted for 12%, while births and deaths accounted for −1%.

Most of the population (as of 2000) speaks German (2,116 or 94.5%) as their first language, Serbo-Croatian is the second most common (23 or 1.0%) and Italian is the third (20 or 0.9%).
There are 19 people who speak French and one person who speaks Romansh.

As of 2008, the population was 49.8% male and 50.2% female.
The population was made up of 1,108 Swiss men (44.3% of the population) and 137 (5.5%) non-Swiss men.
There were 1,143 Swiss women (45.7%) and 113 (4.5%) non-Swiss women.
Of the population in the municipality, 668 or about 29.8% were born in Wilderswil and lived there in 2000.
There were 970 or 43.3% who were born in the same canton, while 298 or 13.3% were born somewhere else in Switzerland, and 234 or 10.5% were born outside of Switzerland.

As of 2010, children and teenagers (0–19 years old) made up 21% of the population, while adults (20–64 years old) made up 61.5%, and seniors (over 64 years old) made up 17.6%.

As of 2000, there were 927 people who were single and never married in the municipality.
There were 1,094 married individuals, 125 widows or widowers and 92 individuals who were divorced.

As of 2000, there were 283 households that consist of only one person and 63 households with five or more people.
In 2000, a total of 911 apartments (76.4% of the total) were permanently occupied, while 211 apartments (17.7%) were seasonally occupied and 71 apartments (6.0%) were empty.
 As of 2010, the construction rate of new housing units was 8.8 new units per 1,000 residents.
The vacancy rate for the municipality, in 2011, was 0.95%.

The historical population is given in the following chart:
Wilderswil has a population (as of December 2018) of 2,658.  As of 2010, 10.0% of the population are resident foreign nationals. In the period from 2000 to 2010, the population changed at a rate of 12.7%. Migration accounted for 12%, while births and deaths accounted for −1%.
Most of the population (as of 2000) speaks German (2,116 or 94.5%) as their first language, Serbo-Croatian is the second most common (23 or 1.0%) and Italian is the third (20 or 0.9%). There are 19 people who speak French and one person who speaks Romansh.
As of 2008, the population was 49.8% male and 50.2% female. The population was made up of 1,108 Swiss men (44.3% of the population) and 137 (5.5%) non-Swiss men. There were 1,143 Swiss women (45.7%) and 113 (4.5%) non-Swiss women. Of the population in the municipality, 668 or about 29.8% were born in Wilderswil and lived there in 2000. There were 970 or 43.3% who were born in the same canton, while 298 or 13.3% were born somewhere else in Switzerland, and 234 or 10.5% were born outside of Switzerland.
As of 2010, children and teenagers (0–19 years old) made up 21% of the population, while adults (20–64 years old) made up 61.5%, and seniors (over 64 years old) made up 17.6%.
As of 2000, there were 927 people who were single and never married in the municipality. There were 1,094 married individuals, 125 widows or widowers and 92 individuals who were divorced.
As of 2000, there were 283 households that consist of only one person and 63 households with five or more people. In 2000, a total of 911 apartments (76.4% of the total) were permanently occupied, while 211 apartments (17.7%) were seasonally occupied and 71 apartments (6.0%) were empty.  As of 2010, the construction rate of new housing units was 8.8 new units per 1,000 residents. The vacancy rate for the municipality, in 2011, was 0.95%.
The historical population is given in the following chart:
Wilderswil