Bryan Smolinski and Tyler Pyatt also scored for the Canucks to help Vancouver build a three-point lead over the second-place Minnesota Wild in the Northwest Division.
"It wasn't our best game, but we found a way to win," Canucks coach Alain Vignealut said. "Our power play got us two goals and two points, that was the difference tonight."
Johnson, the third overall pick in the 2005 draft, left the University of Michigan after two seasons and signed with the Kings on Tuesday. He was originally drafted by the Carolina Hurricanes but Los Angeles acquired his rights in a trade on Sept. 29.
The 20-year-old had an impact in his NHL debut, but not as he likely wanted.
With the game tied 1-1 five minutes into the second, Canucks winger Jan Bulis flipped Johnson head over heels with a hip check along the right boards. The hit immediately drew Kings forward Scott Thornton into retaliating against Bulis, leading to a roughing penalty.
Vancouver took the lead on the ensuing power play as Sedin batted in a rebound. Pyatt added a backhander from the slot off a pass from Sedin 6:20 later to give the Canucks a two-goal advantage.
"It was a good hit; I figured something like that would happen sooner or later," Johnson said. "It's good that I got that first one out of the way. In college, it's easier to get around a player like that."
Dustin Brown and Anze Kopitar scored for the Kings. Kopitar drew the Kings to 3-2 at 6:23 into the third period but could not get the equalizer against Luongo. Sedin scored his second goal into an empty net in the final minute.
"They allow a lot of shots, so they must rely on his saves," Kopitar said. "(There's a reason) he is the best goalie and has the most wins in the league."
Henrik Sedin had three assists for the Canucks, who were out shot 34-21.
"They put a lot of pressure on us and I though that they fought hard," said Luongo.
The teams matched power play goals in the opening period. A pass by Pyatt deflected off a Kings defender and fell to Smolinski in the slot where he wristed shot past goalie Sean Burke to give the Canucks a 1-0 lead.
Brown drew Los Angeles even, deflecting in a shot by Jamie Heward for his 16th goal.
- Kings defenseman Rob Blake, who like Johnson originally joined the team at the end of his college season with Bowling Green in 1990, missed Johnson's debut with a neck strain.
- Los Angeles center Derek Armstrong returned after missing nine games with a knee injury.
- Vancouver defenseman Sami Salo, who returned to the lineup Tuesday after missing three games due to a groin injury, was back out of the lineup Thursday.