Johansson had two assists, and Tyler Pitlick and Ryan Hartman scored for the Wild (18-9-5), who have won three straight and are 9-0-2 in their past 11 home games. Jesper Wallstedt made 34 saves.
"It was a good game. It was a hard game to win," Minnesota coach John Hynes said. "You know, I thought both teams were, as I said, it was a fast paced game. It was competitive. There was emotion to it. I thought both teams had some different adversities throughout the game, but I like the fact that we competed at a high level, and I thought we needed to do to win."
Tim Stutzle and Dylan Cozens each had a goal and an assist for the Senators (14-13-4), who have lost four of their past five. Merilainen made 22 saves.
"I liked it. It was a really strong road game," Ottawa coach Travis Green said. "I thought we controlled the play for a lot of the game, probably seven or eight minutes in the second period that I might not have liked, but other than that, we played a real strong game tonight. It's unfortunate that we didn't get two points, never mind one."
Pitlick made it 1-0 at 3:54 of the first period, tipping in a Jared Spurgeon shot. It was Pitlick's first goal of the season and his first since November 25, 2023, when he was with the New York Rangers.
Hartman increased the lead to 2-0 with a power-play goal at 16:02, redirecting a pass from Johansson at the side of the net.