A security operation swung into action on Friday night around 9.30 pm after a suspicious object was found at the property in Kinnaird Street in the New Lodge.
Army Technical Officers were tasked to the scene and declared the object was a viable device.
It has made safe before being taken away for forensic examination.
Several homes were evacuated during the alert which ended before 2 am this morning.
Detectives are appealing for anyone who noticed anything suspicious in the area to contact them at Reactive and Organised Crime at Musgrave PSNI station on the 101 non-emergency number 101, quoting reference 1411 03/02/17.
Alternatively, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers on 0800 555 111.