United Continental said on Wednesday that its passenger service employees had elected to be represented by the International Association of Machinists union.
The company, formed from the 2010 merger of United Airlines and Continental Airlines, is the parent of the new United Airlines, the world's largest carrier. It has been working to establish joint labour contracts with its work groups and will now bargain with the IAM.
United has more than 16,000 passenger service employees who work as customer service agents in airports and reservation centres. The IAM had represented the workers from the former United Airlines, while the Continental employees were not unionised.
"We have a long-standing relationship with the IAM," said Megan McCarthy, a spokeswoman for the airline. "We will work closely with them on a contract for all of our passenger service co-workers that is fair to the company and fair to employees, and we will continue to work together with them."