"There was a time in America when most fast-food workers were high-school kids living at home and trying to make some spending money," Comptroller John C. Liu said in a statement issued by his office. "Sadly, in 2013 that is no longer the case."
Many adults trying to support a family work in such restaurants now because higher-wage jobs are not available, he added.
Striking fast-food workers are demanding $15 an hour and "we hope they succeed," Liu said. "Paying them the minimum wage of $7.25 an hour or close to it is unconscionable."
Should the workers' demands fail, Liu said he would push for New York City's minimum wage be raised to $11.50 an hour, a level he said that was "barely enough to lift a worker out of poverty."
The strike that began Thursday is the latest of industry protests that began last fall.
In the pre-Labor Day walkout, workers in at least 58 cities planned to picket restaurants such as McDonald's, Burger King and KFC during peak lunch hours to call for an hourly wage of $15 and the right to unionize without fear of retaliation, USA Today reported.
The nationwide event also was supposed to align with the 50th anniversary of the March on Washington, which was commemorated Wednesday. During a ceremony commemorating the march, President Obama said that while many of the march's goals have been achieved, economic opportunity for all Americans had not.
"For over a decade, working Americans of all races have seen their wages and incomes stagnate, even as corporate profits soar, even as the pay of a fortunate few explodes," he said.
Obama has called for raising the federal hourly minimum wage from $7.25 to $9, but the measure has stalled in Congress.
The fast-food demonstrations come as low-wage jobs dominate employment growth as the nation still recovers from the recession. The Center for Budget and Policy Priorities said more than a quarter of Americans earning less than $15 an hour receive at least one social service, such as food stamps and Medicaid.
Labor officials are tapping into new strategies to unite workers while working to expand the pool of potential union members, USA Today said, noting that the percentage of Americans who are union members fell to 11.5 percent now from 25 percent in 1980.
"There's absolutely a new wave of organizing action among low-wage workers across the nation," Paul Sonn, legal co-director of the National Employment Law Project, said. "In the past, there was a sense it was hard to organize these low-wage industries. Now they've become the centerpiece of our economy."
Corporations have maintained higher wages mean fewer jobs and higher prices.
The Economic Policy Institute said 88 percent of workers in jobs paying less than $10 an hour are older than 20, and a third are older than 40.