Goals from Christopher Samba and Roque Santa Cruz saw Blackburn claim a 2-1 win at St James' Park in front of a 44,935 crowd - the lowest in the Premier League since the stadium was expanded eight years ago.
Samba and Santa Cruz had struck in the first half to give Paul Ince's side a 2-0 lead at the break.
Michael Owen's penalty early in the second half gave Newcastle some hope, but they couldn't summon up an equaliser - and a win for Tottenham Hotspur at Portsmouth on Sunday will leave them bottom of the division.
The game was watched by new interim manager Kinnear, serving the first game of a two-match touchline ban dating back to his last spell in management at Nottingham Forest almost four years ago.
And Kinnear - handed a short-term deal by owner Mike Ashley while he attempts to sell the club - was given plenty to think about by United's first-half performance.
Blackburn were the brighter side in the early stages and Shay Given had to be at his best twice inside the first 20 minutes.
With nine minutes gone the goalkeeper denied Matt Derbyshire at his near post after the striker had the better of Steven Taylor and in the 18th minute he stopped a shot from Santa Cruz.
The ball rebounded to Derbyshire and, with Given stranded, Sebastien Bassong did well to stop his follow up shot on the line.
However, Ince's side kept their momentum up and it was a case of third time lucky in the 31st minute when Samba finally broke the deadlock.
The defender got ahead of Taylor to head a Carlos Villanueva free-kick past Given.
It was to get worse for United four minutes before the break with Santa Cruz delivering another hammer blow to shell-shocked Newcastle.
Brett Emerton swung in a cross from the right and Santa Cruz got in front of Fabricio Coloccini to head past a helpless Given.
And unsurprisingly United were booed off at the break, while Blackburn's fans - who had taunted the home terraces with chants of 'Joe Kinnear, you're having a laugh' - cheered Ince's men off the pitch.
But St James' Park came alive early in the second half, first when referee Steve Tanner waved away penalty appeals after Martin Olsson appeared to handle a Damien Duff cross a couple of minutes after the restart.
Tanner did point to the spot in the 49th minute when visiting captain Ryan Nelsen clattered into Owen just inside the box and Newcastle's skipper stepped up to take the resulting penalty.
Owen drilled it down the middle, deceiving Jason Brown, for his fifth goal of the campaign and third in as many games.
Ince responded to United's resurgence by sending on Owen's old Liverpool colleague Robbie Fowler for Villanueva in the 62nd minute.
Newcastle introduced Shola Ameobi in the 72nd minute, with the striker replacing Geremi.
Shortly after the substitution, Nelsen - already on a yellow card - went straight through Charles N'Zogbia, but Tanner waved away Newcastle's protests and allowed play to continue.
Newcastle's rally continued, but clear-cut chances remained at a premium.
Coach Chris Hughton replaced N'Zogbia with David Edgar in the 82nd minute, while Ince made a double substitution, sending on Andre Ooijer and Jason Roberts for the last five minutes.
Blackburn comfortably held out for the remaining minutes and there were more boos when Tanner called time on the contest.