The deal, which follows a tricky period for the chain, includes 113 cafes and 1,650 staff.
Starbucks has acquired 23.5 Degrees, its largest UK franchisee, as part of a drive to improve customer experience.
The deal sees Starbucks take on 113 cafes and 1,650 staff, expanding its number of company-owned locations in the UK to almost 500.
Starbucks said the move was about further “enhancing the coffeehouse experience for customers”.
It follows a period of turbulence at the chain, which ousted its chief executive Laxman Narasimhan in August after less than a year in the job following a 3% slump in global sales.
Former Chipotle boss Brian Niccol was brought in to turn things around and wrote an open letter to customers admitting the brand had “drifted from our core”. He promised to “elevate” the in-store experience and improve its digital ordering system, especially in the mornings.
Alex Rayner, Starbucks general manager, UK, Switzerland and Austria: “I want to acknowledge the important contributions of 23.5 Degrees and the dedicated green apron partners. This strategic move will enable us to enhance our investment in new locations, elevate our in-store experience, and drive innovation for our UK customers.”
Read more: Trouble at Starbucks: five ways its new CEO can turn the chain around