The firms were chosen from a shortlist of 15 by a panel headed up by the ODA’s interim finance director David Leather.
The selection process was fast-tracked, with pitches made over the past fortnight.
The successful firms will advise on areas including procurement, contract negotiation, planning, infrastructure, transport, utilities and human resources.
ODA head of procurement Morag Stuart said: “I am delighted with the calibre of the firms we have selected. They have a cross section of expertise and it is this breadth of experience which will be invaluable to the ODA over the lifetime of the project.”
The ODA is still searching for a permanent general counsel, with DLA Piper Manchester-based projects partner Peter Rout currently filling the role on secondment.