Tottenham remain in the bottom three of the Premier League after some slack defending allowed Newcastle to triumph.
Abdoulaye Faye headed against the post early on for the Magpies, who took the lead when Michael Dawson's mistake let in Obafemi Martins to fire home.
Dawson also gave Claudio Cacapa room to nod a second goal after half-time.
Robbie Keane replied for Spurs from close range after Darren Bent's header hit the post but James Milner's sweet volley sealed victory for Newcastle.
Tottenham's defence is the most obvious reason for their struggles - they have kept only one clean sheet all season - and skipper Ledley King clearly cannot return from injury quickly enough for their beleaguered boss Martin Jol.
Their frailties at the back were quickly apparent here when a Charles N'Zogbia corner was met at the near post by Faye, who escaped Younes Kaboul's attention and rattled the woodwork with a powerful header.
But, going forward, Jol's side are still a potent force and they almost stole the lead when a quickly-taken Jermaine Jenas free-kick released Keane, whose shot beat Shay Given but was hacked clear by Cacapa.
Tottenham still looked anything but solid though and another mistake, this time a heavy touch by Dawson, allowed N'Zogbia to feed Michael Owen, whose shot was tipped wide by Radek Cerny.
Cerny was only playing because of an injury to Paul Robinson but, given the England keeper's mixed form of late for club and country, his absence seemed a blessing in disguise.
The Czech Republic keeper was relieved to see Geremi's free-kick deflected wide but made a good save to deny Martins at his near post soon after.
Kaboul's failure to deal with a routine Jose Enrique long ball had led to that chance and an almost identical scenario saw the Magpies take the lead just before half-time.
This time it was Dawson who could not clear from the Spaniard and Martins swivelled to fire past Cerny from just inside the box.
Things soon got worse for the visitors as a second Newcastle goal followed swiftly after the break.
Again Dawson was the defender at fault as he was unable to pick up Cacapa, who met Faye's corner with a bullet header into the net.
It looked grim for Jol, who has got used to speculation over his future at White Hart Lane this season, but his side did not lack spirit as they looked for a response.
Six minutes later they were back in the game when Bent headed against the post from Didier Zokora's cross and Keane tapped home the rebound.
Newcastle were clearly rattled and for a spell Tottenham looked like they could salvage something from their evening.
But Spurs failed to maintain their pressure and their resistance was ended with 17 minutes left when Milner crashed home an unstoppable volley after his first effort was blocked by Jenas.
Newcastle remain in eighth place but they are only two points behind fourth-placed Liverpool and boss Sam Allardyce can be content with his side's early progress.
For Spurs it is a different story - and a long, hard winter beckons unless Jol can turn their season around.