The Reds claimed an emphatic 3-0 victory over their Premier League counterparts to move into the hat for the Fourth Round of the FA Cup for the first time in the club's 124 year history.
Marcelo Bielsa made seven changes to his Leeds side, with Pascal Struijk, Gjanni Alioski, Kalvin Phillips and Rodrigo the only Premier League regulars to retain their place at Broadfield Stadium.
However, after a turgid first half of football, it was the FA Cup minnows who took the lead when left-back Nick Tsaroulla danced through the Whites' defence and blasted past replacement goalkeeper Kiko Casilla.
With former 'The Only Way is Essex' and reality TV star Mark Wright watching from the bench, Tsaroulla staked his claim to keep his place in place of the 33-year-old celebrity.
Ashley Nadesan then doubled Crawley's lead just minutes later when his shot somehow squirmed through Champions League winner Casilla, before Jordan Tunnicliffe fired home after Leeds failed to clear a free kick.
Wright did manage to get a brief introduction to the fray in injury time, but it was his determined teammates who deserve the credit.
Although this much-changed Leeds side were admittedly flat, Town manager John Yems can be incredibly proud of his giant killers.
Former Tottenham youth player Tsaroulla, whose inclusion was Crawley's only change from last weekend's win at Bolton, escaped the attentions of four Leeds players as he drove into the box and drilled his first senior goal into the bottom right corner.
The home dugout had barely finished celebrating the opener when the advantage was swiftly doubled.
Nadesan burst into the 18-yard area on the right and, with no support, opted to unleash a low drive which bobbled and beat former Real Madrid keeper Casilla at the near post.
Crawley, flying high in the fourth tier, were seeking to make it 10 games without defeat and put the result beyond doubt with 20 minutes to play.
After Sam Matthews' free-kick into the box, Nadesan's effort was denied by Casilla, only for Tunicliffe to force the loose ball into the roof of the net.
There was never any threat of a Leeds comeback and substitute Watters could have added further gloss to the scoreline.
He found his path to goal blocked after rounding Casilla, while manager Yems also used the comfortable situation to bring on former The Only Way is Essex star Wright for the final moments.
Bankes' full-time whistle promoted celebratory scenes from the home side as they cruised into the fourth round for the first time since 2012.
Leeds United were dumped unceremoniously out of the FA Cup by League Two Crawley thanks to three fabulous second half goals.