Johansson scored the go-ahead goal 9:40 into the third period, tipping in Mathieu Perreault's shot from the left circle, to spark the slumping Capitals to a 2-1 win against the Buffalo Sabres at HSBC Arena.
The goal came on the power play after Sabres goalie Ryan Miller had nearly single-handedly foiled the Capitals' first four opportunities.
"Yeah, it was a great pass by Matty," Johansson said with a smile, noting that he didn't even see the shot coming before having it deflect in off his stick. "I was just trying to get out of the way and it hit me, and I think sometimes that's all it takes."
The win helps right a Capitals team that improved to 2-4 in its past six, with all four losses coming when they surrendered the winning goal in the third period. And the power-play unit finally showed life, capitalizing for only the second time in 23 chances over a seven-game stretch.
Perreault finished with a goal and assist, while Alex Ovechkin had a hand in Johansson's goal, giving him his first point in his past five trips to Buffalo, dating to a two-goal outing on March 5, 2008.
Washington (31-19-10) closes its five-game road swing at Pittsburgh on Monday and inched to within three points of Southwest Division-leading Tampa Bay.
The Sabres are suddenly stuck in neutral in their bid to climb into playoff contention.
Jason Pominville scored the lone goal for a team that's scored twice in opening a six-game homestand with three consecutive losses. The Sabres (27-25-6) remain in ninth place in the Eastern Conference standings, four points behind Carolina.
"It's tough to win when you're scoring one (goal)," Miller said. "You have to be willing to find a way to score some dirty goals and get some pucks to the net."
Miller had no chance on either goal he allowed and finished with 37 saves.
"Ryan played well enough for us to win," forward Paul Gaustad said. "And that's all you can ask of your goaltender."
Perreault opened the scoring 6:09 into the second period by taking advantage of an opportunistic bounce. Matt Hendricks dumped the puck into the Sabres' end high off the boards, and the puck took a strange carom off a divider in the corner. The puck bounced directly to Perreault, who was alone in front of the net and whacked it past Miller.
"I just took a golf swing at it, closed my eyes and it went in," Perreault said. "Sometimes you play a great game and the bounces aren't going to come your way, and then today they came my way, so I'll take advantage of it."
Ovechkin then set up Johansson's goal by driving up the right wing and getting a hard shot off from the circle. Miller got his blocker out in time to make the stop, but the rebound bounced directly to Perreault in the left circle. He blasted a shot that deflected in off Johansson as he was crossing the crease.
The way Miller was playing, the Capitals wondered what it might take to beat him.
"We had like five unbelievable chances and we just knew Ryan Miller was in one of those zones," coach Bruce Boudreau said. "We had to persevere if we were going to succeed. ... We got a little bit lucky. But if you put enough shots at the net, good things usually happen."
Miller stopped the first 21 shots he faced, 16 in the first period alone. He was particularly sharp during a 1:35 span while the Capitals enjoyed a two-man advantage, when he stopped Nicklas Backstrom twice.
The first came when Ovechkin's shot from the left point deflected off two players in front and landed on Backstrom's stick to the right of the net. Miller got across and made a sweeping glove save. A minute later, Backstrom had the puck alone to the right of the net again and whiffed on his opportunity, missing the open side and instead shooting the puck into Miller's pad.
Material from wire services and team media was used in this report.
1 - 0 WSH
1 - 1 Tie
2 - 1 WSH
Interference on goalkeeper