A Scott Dann own goal and a stoppage time effort by Gabriel Obertan sent Newcastle fifth while increasing Blackburn's relegation worries.
Ryan Taylor's 12th minute shot took a heavy deflection off defender Dann and left keeper Paul Robinson helpless.
But Rovers were wasteful, not least when David Dunn missed a penalty after Danny Simpson fouled Anthony Modeste.
Newcastle's Leon Best headed against his own bar before substitute Obertan sealed victory in the dying moments.
Blackburn must be sick of the sight of Newcastle, having lost three of the four encounters between the teams in as many months.
And Rovers will wonder how they did not salvage at least a point in a game they dominated for long periods.
The worry for manager Steve Kean is that his side's next two away games are at Arsenal and Manchester City.
As for Newcastle, this was just the result Alan Pardew demanded after a 5-2 defeat at Fulham and FA Cup exit at Brighton.
Blackburn need influential defender Chris Samba, missing for the fourth successive match, back as soon as possible if they are to claw themselves out of trouble.
Samba has not featured since handing in a transfer request but Rovers, still without a clean sheet in a top-flight game this season, are clearly missing his presence in the back four.
Rovers went behind after a mix-up between Radosav Petrovic and Dann allowed Taylor to take a speculative shot from distance which deflected off Dann and deceived former England keeper Robinson.
It was cruel on the hosts who, for the remainder of the half, did everything but find the net.
Gael Givet had a volley cleared off the line by Simpson while Modeste, making his home debut after signing on loan from Bordeaux, and Junior Hoilett both went close before Leon Best headed against his own bar while trying to clear Morten Gamst-Pedersen's corner.
Petrovic was also unfortunate before tempers boiled over when Hoilett appeared to dive inside the Newcastle area. So incensed was Taylor by Hoilett's actions that the Newcastle player earned a booking from referee Phil Dowd.
Rovers were awarded a penalty two minutes before the break though, when referee Dowd awarded a penalty after Simpson barged into Modeste.
But Krul came to Newcastle's rescue by keeping out Dunn's weak spot-kick and the Dutch keeper was alert to save Givet's tame follow-up.
Blackburn continued to create chances after the interval, with substitute Mauro Formica firing into the side-netting when he should have done better.
But their hopes were ended in injury time when substitute Obertan ended a quick break with the sort of clinical finish Rovers had been so sorely lacking.
Blackburn manager Steve Kean: "We've had enough chances to win three games. I think if you are trying to take positives out of the defeat then we are certainly making the chances but we just weren't ruthless enough.
"After Newcastle scored their deflected goal we dominated the reast of the first half and all of the second half. Performance wise we have to be happy with the way we played for the first 15 minutes, we controlled the game.
"So it is a tough one to take because we at least deserved a point, in fact I'd probably have been disappointed to have got a point. "I'll speak with Chris (Samba) on Thursday and it's been tough for him after wanting to leave. We're delighted he's still here and I'm sure he'll get back on it for us."
Newcastle manager Alan Pardew said: "We had a bit of criticism about the Brighton game and we lost (Yohan) Cabaye, the two Senegal boys couldn't make it, and we still won.
"Great credit to the players and particularly to James Perch. I left him out even though he was excellent at Brighton. But he came into midfield for the second half and we looked a lot stronger in there.
"We've got such resolve in the squad. We've gone up to fifth - it's an outstanding achievement from this football club. To get a win on the back of Brighton was brilliant."