It includes a lump sum of about $3.4m and annual payments for the next 20 years for his rehabilitation and care.
The hospital also paid for Rosevear and his partner Janine Abery to be flown back to New Zealand on a medical plane. The couple were living in London when he took ill and returned home almost four years ago.
Abery, 48, from Wellington, gave up a film industry career as a production coordinator to become his carer. She had worked on hit movies such as the Lord of the Rings trilogy and The Constant Gardener.
When contacted by the Herald on Sunday on Friday, Abery declined to comment about the payout. Rosevear's family - who own and operate the award-winning Mahoe Cheese company in the Bay of Islands - also declined to comment.
But Abery earlier told London-based newspaper the Evening Standard it had been a "long road" to win a settlement.
"It has been more than four-and-half years since Tristan's stroke, and frustrating they didn't see fit to settle earlier than they did," she said.
"I hope the NHS can up its game so nobody else's family has to suffer what Tristan has."
Rosevear has continued his rehabilitation in New Zealand and has attended a help group for stroke victims on the Kapiti Coast.
"He is a different person now, though he has improved tenfold," Abery told the Evening Standard. "He is unable to read, write or speak coherently to anyone who doesn't know him."
Imperial College Healthcare NHS Trust, which runs St Mary's Hospital apologised "unreservedly" for the treatment at its hospital in 2010.
"The standard of care fell below that which we strive to provide," a Trust spokesperson said.
"We carried out an investigation and measures have been put in place to ensure we deliver the safe, high quality care that our patients deserve."
Mark Vivian, chief executive of the Stroke Foundation of New Zealand believed such a high payout for a similar medical blunder here would be unlikely.
"A situation like Mr Rosevear's would probably qualify for compensation from ACC because it was the result of a medical error," he said. "But in New Zealand we tend to underestimate the financial effects of someone having a stroke."