It already owned 50 per cent of the British company and the new deal will see Cazenove become a wholly-owned subsidiary of JPMorgan.
Current Cazenove chairman David Mayhew will remain in his role and welcomed the announcement of the merger.
"The agreement we have reached is a natural extension of our relationship," he said.
"It builds on what we have achieved in the past five years and provides a platform for the next stage of development."
As a shareholder in the company, Mr Mayhew is in line to receive around $32 million from the sale.
The deal is expected to go through in early 2010, subject to approval from shareholders.
JPMorgan Cavenove is currently one of the top corporate brokers in the UK, with Queen Elizabeth among its clients.
The firm is currently advising Lloyds Banking Group on a proposed $23 billion rights offering.
By Claire Archer