Bryant, Gianna and seven others died when the helicopter they were in crashed in fog on 26 January.
In the lawsuit, Vanessa Bryant says the pilot was negligent for flying in such poor weather.
It was filed shortly before a memorial service held in Los Angeles.
Island Express Helicopters and the pilot, Ara George Zobayan, had a "duty to use that degree of care that an ordinarily careful and prudent pilot would use under the same or similar circumstances," the suit says.
