The deceased has been identified as Maimuna, belonging to Krishnapura in the district.
Police said the the scooter suddenly got stuck in a pothole on the highway, following which the woman lost her balance and fell on the road.
A truck proceeding from Thokkottu to Mangaluru then ran over the woman, killing her on the spot, sources said.
The woman had gone to Thokkottu to attend the wedding of a relative. After the wedding, the two were proceeding to attend the Uroos festival at Ullal when the accident took place.