A section of the M2 motorway was closed after the woman was found lying near the Bellevue Bridge on the Antrim Road around 9 pm.
Some reports suggested the woman was aged in her 50s and from the Glengormley area.
The alarm was raised by a passing ambulance crew.
A further ambulance crew and rapid response vehicle were also called to the scene.
Ambulance Service spokesman John McPoland said: “A crew was coming to Belfast from the Antrim direction and came across the incident at the Bellevue Bridge.”
The motorway was sealed off city bound between the Sandyknowes and Fortwilliam junctions causing traffic disruption in the area.