Nearly 1,000 people signed a petition against plans to develop the site in Christchurch, Dorset, and more than 120 people objected to the application.
Local business owners say the loss of parking will damage trade.
Developer Aster says there is alternative parking and the new homes will bring more potential customers.
The £30m plans, approved by Bournemouth, Christchurch and Poole (BCP) Council, mean the police station, magistrates’ court, a pub and two long-stay car parks will make way for 130 new homes, 39 sheltered accommodation units, shops and restaurants.
Stavy Antoniou, who runs Matisse beauty clinic, said: “Like so many high streets, they seem to be destroying them one by one.
“I just feel like it’s really short-sighted of the councils. We have a lot of ladies that visit here on dark, wintry nights who might be worried to be parking so far away.”
James Cocklin, who runs Coffee Pot and Kitchen cafe, said: “New houses would be a positive but obviously, with the loss of the parking, we’ll be losing the other customers. We’re no Amazon so these are the problems that everybody’s facing.
“And you want people to come into town – if you take the parking away, where are they going to go?”
Aster senior land manager Lindsey Aldington said: “I think they’ve got a whole new base of potential customers right on their doorstep.
“Their customers really shouldn’t be put off by having to change from the car park they’re used to to one across the road.”
In its report, BCP Council said the scheme would provide considerable economic benefits while contributing towards housing targets.
Construction is expected to start next year.