The record-breaking 8,115 square-metre (87,350 square-feet) poster consisted of a series of massive black plastic sheets, with the words "What would you do if your income was taken care of" in gold lettering.
It was set up in a large diamond-shaped open space in central Geneva called La Plaine de Plainpalais.
The group behind the installation, Basic Income Switzerland, wants all adults in the wealthy alpine federation to receive an income of at least 2,500 francs ($2,500, €2,265) per month.
The minimum income proposal will be put to popular vote on June 5th, one of a series of measures up for approval during the country's three-monthly referenda.
In October, campaigners submitted more than the 100,000 signatures needed to call a referendum.
A minimum income is different from a minimum wage, and supporters say it would provide a safety net that severs the link between income and work.
The measure seeks to legally ensure that no adult in Switzerland has to live on less than 2,500 francs a month, including those who do not qualify for unemployment insurance and those who do not want to apply for it.
Experts say implementation would almost certainly require a tax hike and some fear it will encourage people to stop working.
"What we are seeking in this referendum is that everyone in Switzerland has enough money to exist," said Marilola Wili, a spokeswoman for Basic Income Switzerland.
The group believes people should be free to turn down work they do not want and to pursue their interests with the security of having their basic financial needs met.
Asked about the merits of a Guinness Record stunt, Wili said campaigners felt the notion of a minimum income was "the biggest question on Earth."
"We decided we don't only want to say this, but we actually want it to be the biggest question on Earth," and so produced the world's largest poster that physically posed the question, Wili told AFP.
Guinness World Records verified that the poster was the biggest ever. Images of it were expected to be shown at New York's Times Square later Saturday.
The previous record of 7,165 square meters was set in the Iraqi city of Karbala by Fareed Lafta, a peace campaigner who gained prominence through his involvement with extreme sports.