SJP has dumped Pimco in favour of a three-strong team of external fund managers on its multi-asset fund.
The restructure sees teams from Invesco Perpetual, Schroders and US-based Payden & Rygel now manage the fund.
The objective of the fund remains unchanged - to provide a balance of income and capital growth over the medium to long term. It has returned 7% in the 12 months to the end of August, recovering from a difficult 2013 when it lost 7.6%.
Investors in the Multi Asset fund will also benefit from a reduction in the external management charge.
The multi-asset fund had been managed by a Pimco team comprising Mihir Worah, Curtis Mewbourne and Vineer Bhansali and controls some £285 million in assets following its launch in April 2012. The overall mandate size is £944 million.
SJP's decision follows the shock exit of Bill Gross from Pimco on Friday.
Mike Hodgson, head of risk managed investments and structuring within Schroders portfolio solutions team, becomes responsible for the equity component of the multi-asset fund.
Meanwhile Payden & Rygel (P&R), based in Los Angeles, manages assets of over $82 billion and focuses on generating returns through identifying investment opportunities from a global universe of corporate bonds and other fixed interest securities.
SJP is also launching the UK Income fund, which will run by AAA-rated Chris Reid of Majedie.
The fund will be based on Reid's top performing Majedie UK Income fund, which has returned 16.2% in the 12 months to the end of August, making it the fourth top performing fund in its peer group over that period.
Chris Ralph, chief investment officer at SJP, said: ''The changes to the Multi Asset fund are very exciting. The new structure allows our clients to benefit from the combination of the three teams’ different skills and approaches and the potential for strong returns and greater capital protection over the medium term.
'Payden & Rygel is another fund manager with which St. James’s Place has an exclusive relationship in the UK retail market.'
He added: 'Our investment management approach ensures that our clients will benefit from a seamless transition to these new arrangements.
'These changes provide a further demonstration of the benefits of our investment approach and rigour of the work undertaken by the investment committee and our investment consultants.'