The pub with rooms was officially opened following its multi-mullion pound redevelopment by retired police inspector John Proud.
The ground floor of the Grade II listed building has been transformed into a series of contemporary, relaxed spaces for people to eat and drink inside, while a self-contained snug called The Custody Suite provides seating for 20 people.
The Inn Collection Group purchased the site in 2020 having been empty since 2017.
Sean Donkin, managing director of The Inn Collection Group, said: “This has been a particularly exciting project for us. We are delighted with the transformation of this very special building.
"It has such a fascinating past we wanted to pull out all the stops to give justice to this. Giving it a brand new purpose and watching it come to life with customers of all ages after so long is brilliant to see.
“Northallerton is a great country town with bags of character and The Northallerton Inn is at the heart of it. We are very happy to be trading and being part of the community here, with a new venue that local people and visitors can enjoy, providing year-round food, drink and accommodation services.”
The Inn Collection Group’s portfolio includes the Hogs Head in Alnwick, the Bamburgh Castle Inn at Seahouses, Commissioners Quay Inn in Blyth, The Amble Inn in Amble and the Lindisfarne Inn at Beal.