The Sunderland winger rounded off a swift counter-attack with a clinical left-foot finish to ensure his side secured a 1-0 Premier League victory over Newcastle.
It was the third season in a row Johnson has scored at Newcastle, and the former Middlesbrough man revelled in being Sunderland's match-winner, as they reeled of a fourth successive victory over their arch-rivals for the first time in their history.
Johnson told the club's official website: "It's up there with the best moments of my career, definitely in the top three, scoring at the Gallowgate End in the last minute and in those circumstances.
"I can't describe the feeling, to be honest.
"I was a bit disappointed with the chance I'd missed previously and wanted to make up for it.
"[When the chance came] I could feel everything around me but you have to black everything out in circumstances like that keep your cool.
"The rest is history, as they say."
Both sides had numerous opportunities to secure all three points, but Johnson felt Sunderland were worthy winners.
He added: "We generated clear-cut chances and on another day could have been out of sight.
"I thought we dug deep and deserved the win overall.
"There must be some history made with three goals in a row in a derby away from home and those wins - personally it was a great day for me."
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