The deal includes 43 Harris & Hoole sites, including 12 high street and 31 supermarket locations.
It follows Tesco's sale of the Giraffe restaurant group to Boparan Restaurant Holdings, owner of the Harry Ramsden’s chain, earlier this month
Caffé Nero intends to retain the Harris & Hoole brand and expand the business to increase its share of the UK’s £7.9bn coffee market.
Gerry Ford, chairman and chief executive of Caffé Nero, said: “Today’s acquisition is the start of an exciting new journey for both Harris & Hoole and Caffè Nero.
"Harris & Hoole has a strong reputation for high quality coffee and that is what Caffè Nero is all about.This focus on coffee quality coupled with their enthusiastic and knowledgeable baristas give me reason to be excited about developing and growing the Harris & Hoole business over the coming years.”
Harris & Hoole was launched in 2013 as part of a partnership between coffee chain Taylor St Baristas and Tesco.
The supermarket bought out the remaining share of the company in February to take full control of the business.
London-based Caffé Nero operates nearly 700 stores worldwide across the USA, Poland, Turkey, Cyprus, Ireland, and the UAE.