Adrian Lam's men held their nerve in the frantic final exchanges that saw Jonny Lomax cross to give Saints hope only for Tommy Makinson to miss an 89th-minute conversion that could have forced a golden point extra period.
Leigh had trailed 8-0 after a bruising first period in which they were almost constantly on the back foot, before tries early in the second half from Ollie Holmes and Zak Hardaker turned the match on its head.
Their win signals an amazing achievement for the Leopards, who last featured in the showpiece occasion in 1971 and who less than 12 months ago were lifting the 1895 Cup for second and third-tier teams at Tottenham.
Since then the club's trajectory has been remarkable and they headed to the Halliwell Jones Stadium in Warrington sitting in an improbable second place in the Betfred Super League with 12 wins from their 13 matches.
This story is from the July 23, 2023 edition of MEN on Sunday.
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This story is from the July 23, 2023 edition of MEN on Sunday.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
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