The managers will take the Schroder UK Dynamic Absolute Return fund with them as the first product of Tellworth Investments.
They will serve notice at Schroders before moving in the fourth quarter of 2017.
Tellworth will be set up under the umbrella of BennBridge, which recently launched in London to provide operational and infrastructure support to boutique fund management teams.
BennBridge will also provide distribution within UK and European markets. The boutique will be the first to sign up as a client of Australian business BennBridge since it expanded its range of UK services last month.
Marriage said: 'We are pleased to be able to continue our relationship with Schroders, whilst at the same time pursuing a personal ambition to start our own business, Tellworth Investments.
'We remain fully committed to our clients and look forward to working with them, Schroders and the team at BennBridge in the future.'
It is expected that the Schroder UK Dynamic Absolute Return fund will migrate onto the Schroder GAIA platform in the future.
Greg Thomas, chief operating officer at BennBridge, added: 'I am very pleased that Tellworth Investments is set to become BennBridge’s first boutique, and we look forward to working closely with Tellworth and Schroders to support the two funds.
'Since last summer we have been working to build a strong distribution, marketing, compliance and operational platform, which is now in place and awaiting FCA authorisation, and which provides a strong foundation for BennBridge’s future growth.'
Over one and three years Marriage and Warren have returned 36.6% and 36.3% compared to the UK smaller companies average manager return of 25.1% and 38.7% respectively.