The Richard Caring-backed group will launch a 292-cover bar and restaurant across the two-storey space at 66 Victoria Street.
It will open seven days a week for breakfast, brunch, lunch and dinner with a menu including white onion soup with onion Lyonnaise, truffle marscapone and toasted brioche; and malted banana ice cream with chocolate brownie.
The restaurant's design will draw inspiration from the nearby railway station, theatre and Buckingham Palace.
The site traded under Jamie Oliver’s brand until the chef’s restaurant empire fell in to administration in May.
The Ivy has also snapped up Oliver’s former Barbecoa site in St Pauls, which will open as its first standalone Ivy Asia restaurant this winter, as well as the old Jamie’s Italian unit in Cardiff.