Under the proposed rules, anyone carrying out work experience for more than four weeks will be paid at least the minimum wage.
In a speech in Lincoln later today (Friday), Labour leader Ed Miliband is expected to say the internship system in place only benefits the well-off.
He will say: "In this country, if you want a good job in a highly prized sector, you’re often asked to work for free, often for months on end, sometimes even a year. It’s a system that’s rigged in favour of those who can afford it.
"Putting careers in highly prized jobs – in the arts, media, fashion, finance and law – out of reach for huge numbers of highly able young people. It’s not fair. It’s not right."
The PRCA applauded news of the pledge as it follows the association's own efforts to end unpaid internships after it launched the Intern Campaign in 2011.
The association, alongside PRWeek, also aims to promote diversity with the launch of the PR Internships For All scheme.
Francis Ingham, director general at the PRCA, said: "For those looking to abuse the basic right of being paid for the work you carry out, the method has always been obvious: rely on HMRC’s grey area of a ‘worker’.
"We know what a worker is and those peddling the unpaid labour myth to young people know as well. This is a game-changer: one that will hopefully resonate across all parties and one that follows significant work by the PR industry to solve a problem that has blighted young people for far too long."