Joelinton's first Premier League goal proved decisive as Newcastle stunned Spurs on their own patch.
Spurs lacked the inspiration to muster a comeback after the Brazilian's 27th minute opener, the resilient visitors able to see the game out with significantly greater ease than expected.
Story of the match
The game assumed a predictable pattern from the off as Spurs struggled to carve out opportunities against a deep-lying defence despite enjoying plenty of possession.
There was a blow for the visitors on 17 minutes when £16million signing Allan Saint-Maximin, who had been sidelined for the defeat against Norwich, was forced off with a seemingly innocuous injury.
Spurs had a penalty appeal waved away shortly afterwards after Fabian Schar's sliding challenge on Heung-min Son, but it was Newcastle who fashioned the first clearcut chance when Joelinton laid it off to Sean Longstaff, who forced Hugo Lloris to tip his powerful effort over.
Spurs failed to wise-up to the danger posed by the Brazilian, and soon they were made to pay. He found space in between Davinson Sanchez and Danny Rose and calmly dispatched after Christian Atsu, Saint-Maximin's replacement, delivered an excellent dinked cross.
The hosts responded by upping the tempo and enjoyed a much more threatening spell, which peaked with a volley from Son that Martin Dubravka had to palm away.
In the last action of the half, the largely anonymous Harry Kane dug out a cross but Lucas Moura failed to capitalise on Dubravka's misjudgement under pressure from Atsu at the back post.
Newcastle, then, had succeeded in frustrating Spurs until the interval.
Spurs continued to toil in the early part of the second half, prompting Mauricio Pochettino to introduce both Christian Eriksen and Giovani Lo Celso just after the hour mark.
But both struggled to breathe life into their side.
It was not until the 78th minute than fans were expectantly off their seats after Lo Celso knocked it through to Kane. Jamaal Lascelles stumbled and clumsily took him down, but after a VAR review Spurs were somewhat controversially denied a spot-kick.
However, they only had themselves to blame as they spurned a glorious chance moments later. Moussa Sissoko played in a low cross and Lucas could only fire well over with everybody inside the stadium expecting the gaping net to bulge.
Miguel Almiron then whipped the ball just past the post - via a deflection - as Newcastle looked to kill the game on the counter.
Spurs were presented with their final opening in the fourth of six added minutes as Sissoko produced another pull-back, but Kane uncharacteristically fluffed his lines.
Joelinton announces himself
Having cut an isolated figure in Newcastle's opening two games, Joelinton grabbed this one by the horns.
It was an assured finish for the match-winning goal, and thereafter he was a menace, proving too hot for Sanchez to handle.
His movement and his raw power are very valuable assets, and there was plenty of promise in this performance.
Massive result for Bruce
Amid ongoing fan protests, doubts about Steve Bruce were already beginning to creep-in after a resounding defeat at newly-promoted Norwich.
But to respond against Champions League opposition and to execute the gameplan to perfection was a mighty feat. Above all, their unrelenting application will delight the manager.
Still, you feel that if they don't follow this up next week with three points against bottom-of-the-table Watford, much of the good work will be undone.
Big names falter
When a team is struggling, it needs its big guns to step-up, but that simply didn't materialise for a weary-looking Spurs.
Almost everything that Son tried didn't come off, Lucas was guilty of missing two of the best chances and Eriksen failed to inject any real vigour into the attack.
Most disappointing of all was the performance of Kane, who asked very few questions of the opposition centre-halves and made a hash of a potential draw-saving moment. It was an all-round off-day.
Question marks for Spurs
Spurs' impressive summer business has left them hopeful of closing in on Manchester City and Liverpool, but any possibility of a serious challenge will fade if they don't swiftly raise their game following this slow start.
They needed a late rally to beat Aston Villa on the opening day, were fortunate to nick a draw at the Etihad and have now fallen to a defeat which seemed almost unthinkable.
The trip across North London in seven days' time might be the ideal fixture to get them fired-up and ignite their season.
Man of the match
There were plenty of dogged Newcastle displays, but Paul Dummett shone brightest in a five-man backline which had to maintain total concentration under consistent pressure. The Welshman didn't put a foot wrong.
Summer signing Emil Krafth was also instrumental in shutting Spurs out.