The Leeds club stormed to a 20-0 victory at bottom club Abbeydale 2nds to leapfrog Dunnington and seal the trophy with two rounds to spare.
Although the York outfit also triumphed, 18-6 at third-placed Pontefract, to trail Chapel Allerton by a single point, they have completed their fixtures.
Pontefract’s defeat leaves them on 233 points, 41 points behind Chapel Allerton, and means, with only two games left, they cannot catch the champions.
Stuart MacGregor, former world No 3 Simon Parke, Declan Christie, Dom Hamilton and Cameron Ward were Chapel Allerton’s heroes with 3-0 wins over Adam Turner, Phil Scully, Sam Watts, James Biggin and Andrew Mills, respectively.
Dunnington were guided to victory by their top order, with Nathan Lake, Gareth Lumsdon and Michael Andrews coasting home in straight games against Taminder Gata Aura, Neil Cordell and Alex Hodgetts.
The home side claimed the bottom two rubbers 3-2, with Lewis Doughty edging past Andy Cross and George Wileman squeezing home against Matthew Stephenson.
There was also a 19-7 win for Hull & East Riding over Pontefract Seconds, after Fiona Moverley persuaded American world No 27 Olivia Blatchford – her lodger for the Allam British Open in Hull – to make her YSL debut for the home side.
Although Moverley, a wildcard at the Open, went down 3-2 to Matt Godson, Blatchford triumphed 3-1 against Elliot Ridge to help Hull to only their fifth victory of the season.
There were also 3-1 wins for Harry Falconer, Yusef Forster and Glyn Saunders against Adam Taylor, Sam Wileman and Switzerland’s Nadia Pfister, respectively.
Abbeydale battled to a 14-9 triumph at Queens thanks to Kyle Finch’s 3-0 beating of Patrick Rooney, Omar Badr’s 3-2 success against Sarah Campion and Murray Scott’s 3-1 victory over Danny Bray.
The two other rubbers ended in 3-0 wins for Matt Sidaway against Guhan Sethikumar and Connor Sheen over Oli Turner.