All of the country's 26 cantons, and a total 63.5 percent of voters supported the move in a controversial referendum.
"I am relieved, " Christine Bussat, head of the White March association behind the initiative, told public broadcaster RTS.
"I was very worried that this wouldn't pass."
The vote requires Swiss lawmakers to draft one of Europe's harshest laws against those convicted of sexually abusing children or dependant adults.
The government is among those opposed to the automatic, lifelong ban of working or volunteering with kids or vulnerable adults.
It has voiced concern that this leaves no room for legal interpretation on the gravity or nature of the crime.
Bern and other opponents have warned that the ban could potentially be slapped on a 20-year-old who has sexual relations with someone just under the 16-year legal age of consent, or even on underage children who exchange pornographic material.
In another national referendum issue, 88 percent of voters supported a plan to entrench basic medical services in the Swiss constitution.
The constitutional change requires the federal government and the cantons to take whatever means are necessary to ensure there are sufficient family doctors and basic medical services to meet the needs of the population.
The proposal was backed by the government as a counter-proposal to an initiative launched (and subsequently withdrawn) by family doctors, who raised concerns about the shortage of people in their profession at a time when the population is ageing and medical demands are rising.
"That is wrong," the White March association says in its campaign material.
"The initiative is targeted at paedophiles," and not at youths, says the association, underlining that the law to be drawn up will make this clear.
The government has maintained that the new law is not needed as it will overlap with existing legislation.
But supporters of the initiative are adamant that current laws are too lax, allowing for child interaction bans of only up to ten years against paedophiles sentenced to at least six months behind bars.
Anxiety among teachers
Following Sunday's vote, the Swiss parliament will be tasked with drawing up one of Europe's strictest laws against convicted paedophiles.
In Italy, some convicted paedophiles are automatically banned for life from working with children, but other European nations leave the decision on whether to institute such a ban up to a judge.
Swiss Justice Minister Simonetta Sommaruga voiced disappointment Sunday that the initiative had passed.
Translating the text into law will prove a "dilemma", she told reporters.
She said it would not be possible "without violating the constitution" which states the punishment must fit the crime.
Judith Wyttenbach, a constitutional law professor in Bern, told ATS that automatically banning a trained school teacher from practicing his profession for life might be viewed as a breach of the European Convention on Human Rights.
School teachers, meanwhile, called for the initiative to be implemented "in the most reasonable manner possible."
"We don't want to slide towards psychosis like some other countries, like the United States, have done," Georges Pasquier, head of the teacher's union in the French-speaking part of the country, told ATS.
He warned that "perpetual anxiety" among teachers that their words or actions could be misconstrued had a negative impact on their work.
Under Switzerland's direct democratic system, national referenda are held every three months on a vast range of subjects.
Parliament can call a popular vote, or citizens themselves can muster 100,000 signatures in order to put so-called popular initiatives to the vote.
It can often take several years from the time an initiative passes before it becomes law.