The union win, at a Philadelphia store where workers are seeking higher wages, comes as Amazon is also fighting organizing efforts among some warehouse employees and delivery drivers.

Now, a battle lies ahead when working out the first contract between Whole Foods and the unionized workers. "This is going to be the longest uphill battle of our lives, but this is not just for us. This is for the people who come behind us and for the people who have been here," said Khy Adams, a Whole Foods employee.

Workers at a Pennsylvania Whole Foods store voted on Monday to unionize, forming the first union in the organic grocery chain owned by Amazon.