O'Neill's first match as boss of the Black Cats looked like ending in defeat with Rovers 1-0 up and just six minutes left to play.
But David Vaughan's powerful long-range shot drew Sunderland level and, in stoppage time, Sebastian Larsson curled in a free-kick from the edge of the box to give the north-east side a win that took them out of the relegation zone.
"It was surreal, really surreal. Just to get three points on the board is immense," said O'Neill, appointed after Sunderland sacked Steve Bruce.
"I would have given a lot for that, just to have won the game, but mainly - forget about myself -- just for the players," the former Leicester, Celtic and Aston Villa manager added.
"Having lost the game here last time out against Wigan in the circumstances in which they did, and then to go to Wolves and miss the penalty and then lose the game...
"It's only a win, it only gives us a win. We have a million miles to go, but in terms of restoration of confidence, it was great," said the 59-year-old Northern Irishman.
It looked like being yet another day of woe on Wearside for Sunderland when Simon Vukcevic's header gave Rovers, still firmly rooted in the bottom three, a 17th minute lead.
And while O'Neill had always hoped to win his first game in charge of Sunderland -- the club he supported as a boy -- nothing in his imagination prepared him for the frantic finale.
"Even in my wildest dreams, I never thought about those. David Vaughan's equalising goal was just brilliant," said O'Neill, following a start that would have endeared him to the bulk of a near 40,000 home crowd.
Rovers manager Steve Kean was left bemoaning his side's luck, citing a handball against Mauro Formica which led to Larsson's winner and a disallowed Scott Dann goal four minutes before half-time, chalked off after Blackburn's Christoper Samba was ruled to have fouled Sunderland keeper Keiren Westwood.
Kean, who denied any knowledge of a looming financial crisis amidst reports Rovers' Indian owners could struggle to pay players' wages in February, also had to witness Blackburn lose Michel Salgado with suspected fractured ribs, Jason Lowe through concussion and Gael Givet with heart palpitations.
Asked about Givet, he said: "He has had it before and he was feeling as if his pulse was pounding out of his neck.
"The doctor said there was a potential that he could collapse, so we had to just get him off.
"He has had it before in the past when his heart goes out of synch and starts to fire at a different time.
"The doctor said we needed to get him off because we could have ended up with a much more serious situation."
Source: AFP
Source: AFP