This intriguing clash pitted two teams in the thick of a keenly-contested battle for European qualification.
Eddie Howe’s inconsistent side were looking for a fast start, and they managed just that when Alexander Isak fired home a sixth-minute penalty after Vladimír Coufal brought down Anthony Gordon inside the box.
However, that feel-good factor on Tyneside took a turn when Magpies skipper Jamaal Lascelles came off injured following a collision with Michail Antonio and was replaced by Emil Krafth.
Antonio wiped out Newcastle’s lead a mere four minutes later, latching onto Lucas Paquetá’s sublime lofted pass and dispatching a clinical finish past Martin Dúbravka.
Gordon spurned a golden opportunity to restore Newcastle's lead when rising highest to meet Jacob Murphy's inviting cross from the right, but headed wide, before a long-range Bruno Guimarães effort rattled the crossbar.
Those misses proved costly as it was West Ham who struck a hammer blow in first-half stoppage time, as Jarrod Bowen teed up Kudus for a superb close-range strike from Paquetá’s quickly-taken free-kick.
Kudus played a telling role again just three minutes after the restart to turn provider for Bowen, showing superb strength down the left and playing a sublime ball into the path of the England winger to rifle a strike past Dúbravka.
The shellshocked Magpies were desperately searching for a response, but Sean Longstaff inexplicably miscontrolled the ball from Miguel Almirón's cutback and shot wide from deep inside the box.
The incredible extent of the hosts’ injury woes were highlighted when Almirón was withdrawn 10 minutes after being introduced, with Harvey Barnes entering the fray.
Newcastle pressure was growing regardless, and after two quickfire Barnes opportunities, the Magpies were awarded a second spot-kick of the match when Kalvin Phillips clattered into Gordon in the box, and Isak accepted the offer of a Newcastle lifeline with another confident penalty.
An incredible comeback against the odds looked to have been completed thanks to Barnes, who timed his run to perfection and slotted the ball through Łukasz Fabiański's legs to make it 3-3.
The hosts had the final say in this outstanding PL clash which will be remembered for many years to come, as Barnes unleashed an unstoppable strike from distance to send the Gallowgate End into raptures and complete the most astonishing of comebacks.
Howe’s men were reduced to 10 men late on with Gordon shown a second yellow card for kicking the ball away, but that did not detract from a famous day in the north east.
Flashscore Man of the Match: Anthony Gordon (Newcastle United)
