Employees at the Starbucks at 39th and Walnut in University City began the process of unionizing last November.
The store says it voted 14 to 2 in favor of joining Starbucks Workers United.
The union said this is the 11th store in Pennsylvania to join.
It says nationwide more than 9,000 baristas have organized for "justice, fighting for improvements on core issues including respect, living wages, racial and gender equity, and fair scheduling."
In a statement issued Friday, Starbucks said "We respect the rights of our partners to organize and bargain collectively, and we are eager to reach ratified agreements in 2024 for represented stores."
The chain said the vote must be ratified by the National Labor Relations Board before negotiations can begin.