RJF bought the final stake in RJIS from Killik & Co, which co-founded the business in 2001.
The UK business currently supports 68 practices, across a mix of private client investment managers, stockbrokers and investment focused financial advisers.
At of 30 November RJIS serviced 16,000 client accounts representing total assets of £2.57bn.
Peter Moores, CEO of Raymond James Investment Services, said: "The acquisition is a very positive endorsement from our parent company, highlighting our success in the UK and our ambitions to grow the business further."
The parent company was established in 1962 and approximately 64% of its revenue is generated through the private client group and their engagement in wealth management activities.
