Supermacs has been told it has to remove its signage and change its shopfront in Temple Bar.
The fast-food chain took over the building on Essex Street formerly occupied by Hungry Harry's Fish and Chips, and altered the facade without planning permission.
Dublin City Council says the corporate colours and style of lettering is "not of a sufficiently high quality" for the location.
Supermacs is appealing the council's decision to An Bord Pleanála.
