The win gave the Maple Leafs a split of a home-and-home set with Pittsburgh one night after the Penguins erased a 4-1 deficit in the third period before pulling out a 5-4 shootout win.
It was the second shutout this season for Pittsburgh.
Reimer, who was starting for only the second time in 14 games, registered his first shutout since opening night against Montreal in October. It was also a rare appearance for Johnson, who gave Marc-Andre Fleury a rest for the second time in 19 games.
The game featured decidedly less energy than what was on display 24 hours earlier in Pittsburgh, when both coaches were left with some defensive concerns.
The players clearly received the message.
Pittsburgh did manage to get a puck over the goal-line early in the second period, but that goal was overturned because Chris Kunitz was ruled to have kicked it into the net.
The Penguins generated more offense in the middle period, but Reimer kept it scoreless by denying Malkin twice from the side of the net.
Each team had a power play early in the third but couldn't break through. The closest Pittsburgh came was a James Neal shot that rang off the post.
MacArthur broke the deadlock with his 16th goal of the season.
Notes: In 19 career games against the Leafs, Malkin has nine goals and 38 points ... Mike Komisarek and Jay Rosehill were scratched for the Maple Leafs ... Pittsburgh claimed center Cal O'Reilly on waivers Wednesday but he didn't dress.