Johnson's volley settled an entertaining contest as Sunderland made it a record four league wins in a row over their bitter rivals.
The winger, who has now scored in his last three appearances at St James' Park, was unsurprisingly ecstatic afterwards.
He told Sky Sports: "It is a great ground, great atmosphere.
"I always seem to rise to the occasion here. I should have scored earlier on and I'd have been a bit gutted if I had missed that one."
The win, the first Gus Poyet's side have managed since November 3, lifts them to 14th in the table.
And Johnson added: "It's a massive win that gives us a great boost. I think it has been coming."
Team-mate Sebastian Larsson said: "That's the best way to win games, especially the derby away from home. We needed a win."
