The 77-year-old cooking supremo revealed on Twitter the results hours ahead of broadcast, before quickly deleting the post when she realised the mistake.
However, people watching the Channel 4 show this evening were left fuming and some even threatened to switch off after learning who’d already won.
Many took to social media to hit out at Prue with one audience member saying: “No point watching #GBBOFinal GBBOFinal.”
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A second grumbled: “Not bothering watching #GBBOFinal thanks to @PrueLeith!”
“Don't see the point of watching #GBBOFinal now I know who wins. Zumbos Just Desserts on Netflix is much better thankfully,” complained a third.
Nevertheless, others continued to tune in despite the spoiler, tweeting: “Watching #GBBOFinal knowing who's won almost doesn't seem worth it.”
Prue Leith accidentally revealed the results of The Great British Bake Off hours before the show
Prue Leith was slammed by Great British Bake Off viewers
No point watching #GBBOFinal GBBOFinal
Great British Bake Off viewer
Someone else said: “Still watching. Even with the spoiler. #GBBOFinal.”
This evening proved to be a tense watch as the three finalists Sophie Faldo, Steven Carter-Bailey and Kate Lyon were put through their paces.
The first task saw them trying to make 12 small leave, while for the final showstopper round the contestants had to make a traditional Entremet cake.
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Prue is currently on holiday in Bhutan as the furore about the erroneous tweet broke out back in the UK.