Universal produced "United 93," a film depicting the fate of the passengers of the hijacked plane. The donation accompanied an announcement about the upcoming release of "United 93" on DVD.
Universal had already donated more than $1 million to support the memorial.
"We are extremely grateful for Universal Pictures' continued generosity and efforts to raise awareness of the story of Flight 93," said Hamilton Peterson, president of Families of Flight 93, in a statement Thursday. Families of Flight 93 is a nonprofit group that is assisting in efforts to establish the memorial.
Organizers hope to raise $30 million in private funding to build the memorial on a 1,700-acre site outside Shanksville. The total cost is estimated to be $58 million.
Congress four years ago passed the Flight 93 Memorial Act, which established a new national park to honor the victims of the hijacked plane.
Flight 93 was en route from Newark, N.J., to San Francisco when it was hijacked. The official 9/11 Commission report said hijackers crashed the plane into a field near Shanksville as passengers rushed the cockpit.