The long-awaited move means iHeart Media, America's biggest radio group, will end years of corporate limbo during which its private equity owners and its lenders could not agree on how to solve its huge $20bn debt burden.
iHeart said Clear Channel Holdings, the world's second biggest out of home media company after France's JC Decaux, "did not commence Chapter 11 proceedings" and continues to trade.
Bob Pittman, the chairman and chief executive of iHeartMedia, said in a memo to staff: "The entire company – both the Clear Channel and iHeartMedia businesses – will be operating as usual."
He told staff: "William Eccleshare will remain Chairman & CEO of Clear Channel International, and Scott Wells will remain CEO of Clear Channel Outdoor Americas.
"Your day-to-day roles and responsibilities are unchanged and you shouldn’t feel the impact of iHeartMedia’s process.
Industry observers expect bondholders, who own the debt, will take control of Clear Channel once iHeart's Chapter 11 restructuring has completed -- probably in about three months.
Then Clear Channel's new owners could be in a position to sell the business or merge it with another out of home media company at a time of sudden M&A activity in the sector, particularly in digital OOH.
Paul Richards, an analyst at Numis Securities, said "it's good that iHeart is getting its debt under control" and the Chapter 11 process "should be liberating" for Clear Channel as it will be able to decide its future.
"Digital out of home has given the industry a completely new lease of life and it's an industry ripe for consolidation – it’s a very dynamic space," Richards said.
Ocean Outdoor recently announced it is set to float on the London stock market and another DOOH owner, 8 Outdoor, has taken Asian investment.
There has been speculation in the past that Clear Channel and Exterion Media, which is owned by Platinum Equity, could merge.