Richard Trumka, president of the AFL-CIO union, said Mr Puzder's "business record is defined by fighting against working people".
Mr Puzder was one of Mr Trump's earliest campaign financiers, contributing more than $330,000 to his White House bid, reports the Washington Post.
He opposes the Affordable Care Act, also known as Obamacare, claiming it has left working families with less money to spend dining out, spawning a "restaurant recession".
Mr Puzder has brushed off allegations that his fast-food restaurants' racy commercials - featuring scantily clad models gorging on burgers - are sexist.
"I like beautiful women eating burgers in bikinis," he once said. "I think it's very American."
Richard Trumka, president of the AFL-CIO union, said Mr Puzder's "business record is defined by fighting against working people".Mr Puzder was one of Mr Trump's earliest campaign financiers, contributing more than $330,000 to his White House bid, rep