The goal, Vatrano's ninth in his first nine games, continued the winger's remarkable start to his second season a Duck and moved him into a tie with Ottawa's Alex DeBrincat for the league lead.
The assist made McTavish the fifth Duck in franchise history to record a five-game point streak at 20-years-old or younger.
The Ducks would come inches from doubling the advantage on the next shift several times during another net-front scramble, but a couple of saves by Penguins winger Bryan Rust and then another by Karlsson kept it a one-goal game.
Johnston then appeared to give Anaheim that two-goal lead after all with just under two minutes to play in the period, converting a centering pass from Brett Leason behind the net, but Sam Carrick was ruled to have interfered with Jarry and the goal was nullified despite a review.
Instead of the 3-1 Anaheim lead, Pittsburgh would be awarded a power play for the failed challenge and officials added an additional unsportmanslike conduct penalty against Ducks coach Greg Cronin for arguing the call, giving the Penguins a full two-minute 5-on-3 power play.
Pittsburgh would capitalize on that sudden fortune when Malkin beat Dostal with a one-timer from the top of the circle to tie the game.
Zohorna then put the Penguins back in front early in the third, swatting home a rebound after linemate Drew O'Connor kept the Ducks from clearing a rebound in the low slot.
But once again Anaheim would answer in the face of adversity, this time courtesy of the line that has powered so much of the team's offense early in the season. With Pittsburgh trying to break the puck out of the defensive zone up the right wing wall, Mintyukov pinched in and took the puck away, allowing Strome to find McTavish alone in front of the net, where the centerman tucked his shot between Jarry's legs to even the score once again.