The 25-year-old defenseman had spent his entire NHL career with the Kings before being sent to Columbus on Feb. 23 in the deal that sent center Jeff Carter to L.A.
"This one felt good. This has been a really great change for me," Johnson said after getting a goal in his second straight game for his new team. "I've been excited to come to the rink every day. These guys here have a blast here at the rink and it's carrying over onto the ice. Guys are loose and having fun. That's what this game is supposed to be all about."
There weren't a lot of smiles in the visiting dressing room after the Kings lost a game they desperately needed. The loss dropped them one point behind eighth-place San Jose in the scramble for the final playoff berths in the West.
"It was a disappointing start," said Kings coach Darryl Sutter, whose team never led and was outplayed for much of the night. "You break down Columbus' last three games and they've had 2-0 leads on all three teams, Phoenix twice and Colorado. That was our focus, to not get behind and to try and match their energy early. We weren't all able to do that."
Letestu gave the Blue Jackets a 1-0 lead with a redirection 9:14 into the game. His goal 3:07 into the second period completed the scoring.
"It's just a matter of going to the net," he said after his second career two-goal game. "It's tough to score in this League from outside. When you get to the net and get a little puck luck, good things happen."
Johnson and Letestu both spoke about building a team in Columbus, which has made the playoffs just once in its 11 seasons and is all but assured of finishing last in the overall standings. The four consecutive wins are the most for the Jackets since they won five in a row last November, and Columbus is 9-6-1 in its last 15 games.
"It's about building something. Obviously we're out of the playoff race but building a culture, building a foundation for something to work on next year," Letestu said. "Guys are really buying into it and it's showing on the ice."
Johnson has quickly become a fan favorite in Columbus. Carter, the player he was traded for, was booed by the crowd of 14,306 whenever he touched the puck.
"I didn't really think about what was going to happen," Carter said of the fans' reaction. "I just kind of went in and played my game."
One of the loudest cheers came when he misfired on an open-ice shot late in the second period.
Before the game, the Blue Jackets offered free nameplates to fans who brought in Carter's No. 7 jersey with Columbus -- placing a piece of fabric over his name with that of the new No. 7, Johnson.
"Tonight, obviously, I thought our No. 7 was pretty good," Columbus coach Todd Richards said. "He was really good. Scoring a goal, you could see the emotion there."
After Anze Kopitar tied the game at 12:22 of the opening period, Johnson beat Jonathan Bernier with 8.5 seconds left to break a 1-1 tie and give the Blue Jackets the lead for good.
Blue Jackets starting goalie Steve Mason had 16 saves before he left with an injury, with Curtis Sanford coming on in relief to make 13 stops. Mason's left hand was cut by the skate of teammate John Moore after Moore was knocked into the net by Alex Martinez midway through the second period. It took 15 stitches to close the wound.
Richards said Mason would not be able to play for several days, pending a medical evaluation Friday. Mason did return to the bench for the third period.
Carter has two goals since joining the Kings -- both came in the same game. He and former teammate Mike Richards have yet to show the kind of chemistry they had in Philadelphia before each was traded last summer.
Sutter said there was plenty of blame to go around.
"I'm not going to single any of that out," he said of Carter and Richards. "I think the only thing that kept us alive tonight was Jonathan Bernier and our penalty-killing. Other than that, it was pretty much right across."
Material from team media and wire services was used in this report
1 - 0 CBJ
1 - 1 Tie
2 - 1 CBJ
3 - 1 CBJ