The lease for Norwegian Blue has been taken over by The Restaurant Group for its restaurant Coast to Coast, while TGI Friday's has taken over Square.
Both offer American-inspired dining including burgers, chicken wings and Caesar salads, while Coast to Coast also lists deep-pan "Chicago-style" pizza on its menu, plus a host of cocktails.
TGI Friday's places emphasis on sharing platters, including nachos, barbecue ribs, and shrimp, and also offers an extensive drinks menu, including mixed juices and cocktails.
Anthony Jenkins, associate director of Christie + Co, said: "Both restaurants occupy prime locations on the Riverside Leisure Park, close to Norwich railway station, with views overlooking the River Wensum and with excellent passing trade from the cinema and Norwich City FC's Carrow Road ground. These advantages, plus the strength of each of the incoming restaurant brands, should see them have successful futures."
Coast to Coast operates six sites across England, including Portsmouth, Brighton, Newcastle and most recently Leicester, while highly-established brand TGI Friday's has more than 50 sites across the whole of the UK.