The estate comprises 674 leased & tenanted and operator managed community pubs.
Admiral boss Chris Jowsey said it was an “exciting” time for the pub brand even with the problems the hospitality industry has faced during the pandemic.
“This is one of the biggest acquisitions by Admiral to date and delivers on our strategy to build our estate to 1,500 sustainable pubs.
“It is a really exciting step forward for the business and we remain committed to the supportive partnership model, which is highly regarded by licensees.”
Allan Lockhart, New River’s chief executive said it had received a lot of interest after putting the business up for sale in April even with the problems in the sector.
“Over recent years, we have grown Hawthorn to become the UK’s leading community and wet-led pub business,” he said.
Admiral Taverns, which is a joint venture between C&C Group (LON:CCR) and private equity firm Proprium Capital, is focused on wet-led (drink not food) community pub operator, with roughly 1,000 pubs across England, Wales and Scotland.