Three businesses and a council disability team must be rehomed to make way for a £200m business quarter in Sheffield city centre.
Hawleys tyres, Europcar rentals, Egginton Bros knife manufacturer and a learning disability team will be affected by the West Bar Square development.
The project, by Chesterfield developers Urbo, is set to include offices, flats, shops, a hotel and car park on a six-acre site behind Sheffield Crown Court bounded by Commercial Bridge streets.
A planning application is set to be submitted this summer. Urbo staged a drop-in session at Bank Street arts centre this week.
Director Andrew Dainty said there could be up to 400 flats, five office blocks, a multi-storey car park and a public square surrounded by shops.
He added: “We are working with the businesses to find suitable sites for them. Clearly, Hawleys would sooner be left alone. They have a site serving people who work in the city centre. Egginton is a family firm and a fantastic Sheffield business making knives.
“But you don’t do a six-acre site without a degree of disruption and our job is to manage that.”
Several public car parks will be lost, the plans show, including one beside the Crown Court on Corporation Street and another beside the Family Court on Bridge Street.
Several office blocks nearby are being converted to flats. But Dainty said West Bar Square offices would be built to occupiers’ specifications and workers and residents would use the shops, he added.
The massive scheme was revived by Chesterfield regeneration specialist Urbo and Sheffield City Council in 2011 after previous developers Castlemore Securities went bust.
Now, agreements with several parties - including financiers, constructors, existing occupiers, Sheffield City Council and administrators PwC - have been signed.
The scheme could take up to 10 years to complete and involve up to 3,000 construction workers, an Urbo spokeswoman said.