A 40-year-old female pedestrian was pronounced dead at the scene after officers were called at around 4.20am on Friday to the collision between junction 3 and junction 2 of the westbound carriageway.
The stretch of motorway was closed while police carried out investigations, which remain ongoing.
The deceased’s next of kin have been informed and are being supported by specialist officers.
The lorry driver was uninjured.
A police spokeswoman said: ‘We are keen to speak to any motorists who were driving along this stretch of the M27 at around the time of the incident and may have seen anything or has dash cam footage.’
Anyone with information about this incident is asked to call us on 101, quoting 44200127453.