In a Facebook post, Marcello's Father and Son Restaurant said they will be back in business starting Friday.
Although they have decided to reopen, they said there are some limitations and are only offering delivery and pick-up.
Last Wednesday an employee at the 72-year institution said they were closing their door on Sunday, but did not comment why.
The restaurant originally opened at the corner of Diversey and Whipple in Logan Square in 1947, then moved to a larger space at 2475 North Milwaukee Avenue in 1963.
They also have a Northbrook location, at 1911 Cherry Lane, which will remain open as planned.
The restaurant was one of the pioneers of pizza delivery in the city, and specializes in thin crust, tavern-style pizza using a family recipe. It is also famous for its broasted chicken. Pasta, salads, chicken and seafood dishes, and a variety of flatbreads and sandwiches round out the menu.