The Hammers ruined Gareth Bale's return to the Tottenham team as they scored three late goals to steal a draw in north London.
David Moyes' men were dead and buried after Spurs raced into a 3-0 lead after just 16 minutes as Son Heung-min's opener after 45 seconds and Harry Kane's double put them in total control.
They were still winning 3-0 when Bale came on in the 72nd minute substitute but it all went wrong at the end as Manuel Lanzini's stunning stoppage-time strike completed a comeback started by Fabian Balbuena and a Davinson Sanchez own goal.
The result will leave Jose Mourinho utterly sick as they threw away two points for the second successive home game and leaves them unable to impose themselves on the early Premier League table.
For West Ham, the comeback continued a promising start to the campaign following good wins over Wolves and Leicester.
Bale had the chance to steal the headlines as he weaved his way into the box but somehow put his shot wide after doing all the hard work.
In the end, that proved a costly miss as West Ham stole a draw with virtually the last kick.
Spurs could not clear a free-kick and Lanzini stuck a 20-yard shot into the top corner to spark chaotic scenes of celebration.
And apparently those scenes carried on into the changing room; with Randolph telling fans on social media he was devastated they were not there to be a part of the emotional scenes at the full-time whistle.
Replying to a post on Instagram by @westhamlatest, the Republic of Ireland international wrote: "Don't worry mate, we did talk about that.
"Imagine the scenes if the fans were there, wound [sic] have been unbelievable.
"Whistling, cheering, throwing water everywhere," he added. "And just telling each other well done and let's stick to these standards and keep showing that character!"
Darren Randolph has lifted the lid on the incredible scenes in the West Ham changing room after a thrilling 3-3 draw with Tottenham Hotspur.