The apparent discovery of the Musashi, one of the largest battleships in history, comes as the world marks the 70th anniversary of the war's end.
Allen and the team aboard his superyacht M/Y Octopus found the ship on Sunday, more than eight years after their search began, Allen said in a statement issued by his publicity agency, Edelman.
Detailed images captured by a high-definition camera mounted on an underwater probe confirmed the wreckage as that of the Musashi, it said. Allen said on his website that the video and still images showed a valve wheel with Japanese letters saying "main valve handle" which used to be in a lower engineering area, a catapult system used to launch planes, a large gun turret, and one of the ship's two 15-ton anchors. He said the team also found the ship's bow.
Japanese experts said they were eager to study the images to try to confirm the ship's identity.
Kazushige Todaka, head of a private museum specializing in the battleship Yamato, Musashi's sister vessel, said the details in the images matched those of the Musashi, which was the only battleship that sank in the area.
"Judging from the location, it must be the Musashi," Todaka told NHK public television.
The Musashi, commissioned in 1942, sank in October 1944 in the Sibuyan Sea during the Battle of Leyte Gulf, losing about half of its 2,400 crew members. The ship was repeatedly hit by torpedoes and bombs dropped by planes from Allied aircraft carriers.
The naval battle, considered the largest of World War II, crippled the imperial fleet, cut off Japanese oil supplies and allowed the U.S. invasion of the Japanese-held Philippines.
Allen's team found the battleship at a depth of 1 kilometer (3,280 feet) in the Sibuyan Sea using the autonomous underwater vehicle on its third dive after narrowing the search area with detailed undersea topographical data and other locator devices, the statement said.
"The Musashi is truly an engineering marvel and as an engineer at heart, I have a deep appreciation for the technology and effort that went into its construction," Allen said.
He said he is fascinated with World War II history after being inspired by his father's service in the U.S. Army, and that he was "honored" to play a part in finding a key vessel in naval history, and in honoring the memory of those who served aboard the ship.
Allen said he respects the wreckage as a war grave and plans to work with Japan's government to make sure the site is treated properly in line with Japanese traditions. Japanese Chief Cabinet Secretary Yoshihide Suga told reporters that he had no immediate comment.
Suikokai, an organization that supports Japanese navy veterans and conducts research in maritime defense, said that if the discovery is confirmed, a memorial service could be held at the site.
Todaka at the Yamato Museum said the findings, especially during the 70th anniversary of the end of World War II, were a "great achievement" that could inspire many Japanese to revisit the history of the war, whose memory has faded over the past decades.
Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.