"The DNA of the torso matches that of Kim Wall," Danish police announced on Twitter, saying more details would be given at a news conference.
The female torso, with the head and limbs deliberately cut off, was found on Monday in Koge Bay, around 50 km south of Copenhagen.
The 30-year-old Wall, a freelance journalist who had reported for The Guardian and The New York Times, had not been seen since boarding Danish inventor Peter Madsen's submarine on August 10 to interview him for a story.
Madsen, whose website describes him as an "inventepreneur", initially told authorities that he dropped Wall off on an island late on the evening of August 10.
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But he changed his story several days later when he appeared in court, saying Wall died in an accident on board and that he dumped the body at sea in an undefined location of the Koge Bay.
Police have since said they believe Madsen, 46, "deliberately" sank the sub. It was brought to the surface and searched, but found to be empty.