Swiss food giant Nestlé, which also produces Nescafe instant coffee, had announced in May it would pay $7.15 billion (€6.13 billion) for the rights to market Starbucks coffee globally.
Under the deal, some 500 Starbucks employees in the United States and Europe will join Nestlé, the Swiss company said in a statement.
"With Starbucks, Nescafe and Nespresso we bring together the world's most iconic coffee brands," Nestlé CEO Mark Schneider said.
"The outstanding collaboration between the two teams resulted in a swift completion of this agreement, which will pave the way to capture further growth opportunities," he added.
According to the statement, the deal will significantly boost Nestlé's portfolio in North America.
Bloomberg News said Nestlé has struggled in the US for years.
Under Schneider's leadership, Nestlé has made coffee a key priority in its growth strategy, particularly in the US.
Since the CEO took over in January 2017, the group has bought a majority stake in California-based high-end brand Blue Bottle Coffee and acquired Texan brand Chameleon Cold Brew.
Starbucks CEO Kevin Johnson said his firm is also set for a major boost under the deal.
"Bringing together the world's leading coffee retailer, the world's largest food and beverage company, and the world's largest and fast-growing installed base of at-home and single-serve coffee machines helps us amplify the Starbucks brand around the world while delivering long-term value creation for our shareholders," Johnson said.