Maryland workers voted to unite at an Apple store, the first American retail union formed by the tech giant.
The measure was passed by the Towson shop employees 65-33 with about 12 abstentions.
The group posted the following tweet after the announcement: "Now, we celebrate... tomorrow, we continue organising."
This is the third Apple Store to launch a union drive in the year. However, it's the first Apple Store to hold a successful vote.
In May, the Coalition of Organized Retail employees (the new Apple Core union) wrote an open letter to Apple. It stated that its bid was about workers "gaining access to rights that are not currently available to us", but that it didn't want to "go against" or create conflict with management.
New York and Atlanta Apple stores have also moved towards unionization. However, staff in Atlanta have delayed their planned ballot with the Communications Workers of America union, which alleges anti-union activity.
Although unions are not as common in the US as in many European countries they are protected by law. For a company to form a union, it must either voluntarily recognize a union or gather signatures from at minimum 30% of its employees in order for the National Labour Relations Board (NLRB), to hold a formal election.
According to reports, Apple hired a union-expert law firm and compiled "talking points" to discourage employees from signing up.
Motherboard published an audio recording in April of Deirdre, the retail vice president, telling employees that she recognized her right to join a labor union but that it was equally their right not to.
The audio released says, "I am concerned about what it would be like to put another organisation in the middle of the relationship, an organization which does not have deep understanding of Apple and our business."
Towson's employees had the support of an established union, the International Association of Machinists and Aerospace Workers. Robert Martinez Jr., the president of the International Association of Machinists and Aerospace Workers, congratulated Apple employees for what he called "a historic victory".
He said, "They made a great sacrifice for thousands Apple employees across the country who had all eyes on the election."
"This win shows the growing demand to unionize at Apple stores and other industries across the nation."
Apple stated to the AFP news agency that it would not comment on the vote. The vote still needs to be certified by the NLRB.
The union at the Towson store is just one of a number of high-profile campaigns to unionize the US.
Starbucks employees formed their first union in years in New York in December after a successful campaign. This has inspired similar campaigns in many other stores.
Amazon also saw 55% of New York Warehouse workers vote for unionization in April. However, Amazon disputes that ballot and is requesting a rerun.
