The new firm, which is due to be launched later this month but has already secured two contracts, is called Warwick Economics and Development.
It will focus on advising councils and developers on where new schemes should be located, what types of development are required and how that development fits in with local economic strategies.
The firm also plans to offer advice on new ways of funding projects when the resources available are limited.
Managing director Georgia Siora told Planning that she resigned when DTZ decided to close its economic development and regeneration department earlier this year.
She said: "I realised there was still a market for bespoke advice on economic development strategy for developers and local authorities.
"It is a very interesting time for economic development, particularly as the Government is abolishing regional development agencies, but many of the new local enterprise partnerships have yet to become fully established."
Siora has hired four people, two of whom worked with her at DTZ.
Last week, DTZ posted annual pre-tax losses of £3.4 million. A DTZ spokeswoman said: "Our clients are focused on the delivery of real estate projects. To meet their needs, our development consulting business is now focused on delivery, rather than strategy-based work."