The firms were expected to use the MIPIM Property Show in Cannes to unveil the agreement through which they will bid for projects to work on together.
Under the deal, which has been a year in the making, they will work for clients under a single letter of engagement. One firm will then subcontract work to the other.
Joint operations will be overseen by a management board composed of Currie & Brown's joint senior partner Doug Leedham and partner Andrew Wheaton, and Ernst & Young Real Estate Group's managing partner Eugene Bannon and partner Rob Oldham.
Although QSs Gardiner & Theobald and Davis Langdon & Everest have announced worldwide alliances with other QSs in the past two years, industry sources said the Currie & Brown deal is the first with an accountant.
The alliance will combine Ernst & Young's strategic and business advice with Currie & Brown's cost, contract and project management expertise. The idea is to offer clients a range of services that cover the lifecycle of a building, from feasibility studies, funding and procurement, to risk management, construction and maintenance.
Ernst & Young's Bannon said: "I wasn't convinced we could grow organically all the services our client base now demands. Currie & Brown were thinking the same. We will be trying to identify situations in the marketplace where offering comprehensiveness is best."
Leedham said: "There is a great deal of synergy between our two firms that should lead to some exciting prospects. As well as the self-evident benefits of working together, both organisations are committed to establishing innovative and creative services."
Wheaton said that neither side had entered into the deal lightly. Each had vetted the other to ensure its reliability. He added that there were no plans for Ernst & Young to buy Currie & Brown.
Accountants and QSs have competed for work for some time , particularly on client relocations, but each has weak points.
Accountants can charge higher fees, but they may lack expertise on certain projects. QSs, although admired for their cost control abilities, are criticised for lack of vision and command lower fees.