The 27-year-old winger struck with seconds of normal time remaining at St James' Park to silence the home crowd and condemn the Magpies to a third consecutive home defeat by their arch-rivals.
Johnson and his team-mates celebrated on the pitch in front of the travelling fans high in the stand at the Leazes End long after the final whistle as the bragging rights remained on Wearside.
He said: "We've given them something to make their Christmas even more special now
It's great to win four-in-a-row
Whatever happens now, we're in the history books as the team who did it.
"I'm not sure how many more times that will happen."
If Sunderland had to wait to prolong Newcastle's agony, it was no less deserved as they created a series of chances to win the game long before they did.
Indeed, Johnson himself was guilty of a bad 77th-minute miss, although head coach Gus Poyet revealed after the game that he was about to substitute the England international until he saw him get in behind the home defence to create that opportunity.
Poyet's change of mind was richly rewarded when the midfielder started and finished the game's decisive move and fired past keeper Jak Alnwick from substitute Will Buckley's lay-off, his third goal in as many visit to St James'.
Johnson said: "I've done well there in recent years and it was a great highlight
To be honest, the chance I missed, I should have scored.
"We had so many opportunities to kill the game, but we stuck with it and luckily I got another chance and put it away.
"It was a little bit end-to-end in the second half and they pushed their attacking players on, but I thought we always looked a threat on the counter-attack."
Newcastle were intent on restoring local pride and started at break-neck speed, buoyed by the visitors' misfortune in losing specialist full-back Anthony Reveillere to a calf injury during the warm up.
With skipper John O'Shea asked to line up at left-back it meant that Gus Poyet's rearguard comprised of four central defenders and the Black Cats found themselves defending deep and in numbers and under extreme pressure.
But they survived and eventually eased themselves into the game, and with Sebastian Larsson and Jordi Gomez orchestrating and Steven Fletcher and Connor Wickham menacing, they forced their way into the ascendancy.
Fletcher was denied by the crossbar and Wickham by young keeper Alnwick before the break, while both Gomez and Johnson might have scored.
Costel Pantilimon had to pull off stunning saves to keep out goal-bound shots from Ayoze Perez and Moussa Sissoko, and his heroics were ultimately embellished by Johnson's last-gasp intervention.
The win was just Sunderland's third in the Barclays Premier League so far this season and ended a frustrating run of draws, and they will hope to build upon it on Boxing Day when struggling Hull head for the Stadium of Light.
Johnson said: "It's been coming, I think
We have played quite well in games, but just don't seem to have won them or struggled to score goals
But you only need one and we did that.
"Newcastle had had a tough week with a young keeper in goal
We tried to put him under pressure and I think we were quietly confident going into the game thinking we could win again.
"It made it difficult with Anthony pulling out - I don't think Sheasy has played there for 10 years - but they didn't cut us open as much as they'd have liked and we looked solid."
Source : PA
Source: PA