The Black Cats partied in their dressing room long after the final whistle.
And Johnson said: "This win has been a long time coming.
"We have been suffering in recent weeks, a lot of the lads have been low and to get a great result like that lifts everyone.
"We've had a couple of good results over the season, but nowhere near enough with the players we have.
"If we can keep playing like that then we will have no problems staying up."