The helmsman was under the influence of alcohol and talked on the phone, so he did not see the Danish cargo ship Karin Høj but the ships collided in the water between Ystad and Bornholm.
After the collision, the Danish ship capsized and one of the two crew members was later found dead, the other is still missing.
The 30-year-old British helmsman was first arrested at Malmö District Court on suspicion of gross sea drunkenness, gross negligence in maritime traffic and gross causing another person's death.
Then he only admitted negligence of the normal degree.
Delivered to Denmark
Danish police and prosecutors later requested that he be extradited to Denmark.
He was charged in Denmark with "negligent manslaughter", which in Swedish corresponds to "causing another person's death".
He was also charged with driving the ship on after the collision without alerting or helping the crew on Karin Høj.
During Thursday's court hearing at Copenhagen District Court, the Briton pleaded guilty to all the crimes he was charged with.
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The ship accident outside Ystad - in 60 seconds