The number fell to 425 in 2013, a 65 percent drop from 1,198 in 1990, according to Factuel, a public affairs programme that aired Thursday on French-language state broadcaster RTS.
Of this total, 175 were aged from newborns to four years old.
The rate of adoption in 2013 translated to around 20 per 1,000 births, compared with around 20 per 1,000 in the 1980s.
Societal changes in Switzerland combined with stricter international laws governing adoption contributed to the lower numbers, Factuel said.
Domestically, advances in reproductive medicine have reduced the demand for people wanting to adopt children in order to have a family.
There are also fewer unwanted pregnancies and single mothers are more readily accepted than in the past, Factuel said.
In 2001, Switzerland passed a law on adoption based on the Hague Convention of 1993 on the international rights of children that stiffens the requirements for adoption.
This has led to longer procedures for adoption, the programme noted.
Also, the economic situation has improved in many countries, such as those in South America, reducing the number of kids needing new homes.