Irina Lucidi, the mother of Livia and Alessia Schepp, told the Tribune de Geneve newspaper she was driven by the "need to do something" for her children, a "gift" for their seventh birthday.
The girls disappeared at the end of January with their father Matthias.
He threw himself under a train in southern Italy a few days later, after having sent a letter to his estranged Italian-born wife in which he told her he had killed the fair-haired girls and that they were "resting in peace in a quiet area".
Lucidi said the foundation, to be modelled on similar nongovernmental organisations in other European countries and named Missing Children Switzerland, would help address "a legal void".
"Today in Switzerland there are few plans in place for dealing with cases of minors disappearing", she said, adding the first 24 hours after a disappearance were crucial.
A 24-hour telephone hotline in four languages will be set up by January 30th -- a year since the girls disappeared.
Investigations by Swiss, French and Italian police have yielded no trace of the twins.
"The investigations are continuing," said Lucidi, adding: "We hope to find an answer."