The Stanley Cup champions dealt their top defensive prospect and Oleg Tverdovsky to Los Angeles on Friday for defenceman Tim Gleason and centre Eric Belanger.
Johnson, the third overall pick from the 2005 NHL entry draft, resisted recent offers to sign with the Hurricanes because he wanted to play another season at the University of Michigan.
It forced Carolina to make a move because they are in need of defensive help right away. The Hurricanes lost defenceman Aaron Ward to free agency in the off-season and will be without Frantisek Kaberle for up to six months while he recovers from shoulder surgery.
In Gleason, they get a former first-round pick who had two goals and 19 assists in 78 games during his sophomore season with the Kings. The 23-year-old, who will make US$1.2 million this season, was acquired by the Kings from Ottawa for Bryan Smolinski at the trade deadline in 2003.
Belanger, 28, set career-highs with 17 goals, 20 assists and 62 penalty minutes last season, his fifth with the Kings. He will make $1.3 million this season.
"This deal improves our forward lines and adds a very good, young defenceman with NHL experience to the Hurricanes," Carolina GM Jim Rutherford said in a statement. "Eric and Tim strengthen the balance of our team."
Tverdovsky, 30, played in 72 games last season, scoring three goals with 20 assists and 37 penalty minutes. He has $5 million and two years left on his contract.
The Kings will be his fifth team in his 12th NHL season. In 687 career games, he has recorded 77 goals and 236 assists.