Following this emphatic win, Kanturk have now moved ahead of Newcastle West by four points with St. Mary's back in third six points behind the Duhallow side.
It was the Kanturk pack that laid the foundation for this victory as they had the Limerick side on the back foot for long periods in the game and the Corbally side never got close to the Kanturk line to threaten scoring a try.
The first scoring chance fell to Kanturk but Stephen McAulliffe was off target with his penalty effort after thirteen minutes.
Johnny O'Sullivan made a great break for Kanturk and with just the full back to beat he chipped the ball ahead but Connor Kinnane won the race to deny the home side a try.
The deadlock was broken five minutes from time when quick ball out the Kanturk back line saw winger Kealan Buckley touch down in the corner.
Two minutes later Mary's opened their account with a penalty from Ben Martin to leave the score 5-3 in favour of Kanturk at half time.
Despite playing into the wind in the second half Kanturk moved Mark Healy to out half and brought in Phillippe Trippier in the center.
Mary's went ahead with a penalty from Martin on fifty minutes but minutes later a Healy penalty went under the crossbar.
Kanturk's pack with Johnny O'Sullivan, Dan McCabe and Bryan O'Neill prominent began to get the upper hand and after a series of penalties close to the Mary's line scrum half Paul Cotter found a gap to put Kanturk back in front with fifteen minutes remaining.
A great break up the wing by Kanturk's substitute Sean Cremin was halted by a big tackle by Ross Kelly.
Kanturk continued to put on the pressure and when the ball went out the backs Luke McCabe burst through to score his side's third try.
Two minutes later Kanturk secured the bonus point when Mark Healy was on hand to finish off a great run by Johnny O'Sullivan.
Kanturk: P Earlie; J Duggan, L McCabe, M Healy, K Buckley; S McAulliffe, P Cotter; B Kelliher, C O'Sullivan, B O'Neill; B Buckley, M O'Neill; K O'Leary, J O'Sullivan, D McCabe.
Replacements used: P Trippier, S Cremin.
St. Mary's: C Kinnane; B Kinnane, B Martin, J McNamara, R Kelly; B Sargent, O O'Byrne; B Kelly, D Fitzgerald, R Brockert; B Duggan, R Hartigan; R O'Donnell, J Sheerin, B Downey.
Replacements used: B Purcell, P McMahon, S Frawley, B Gibbons.
Referee: F Austin (MAR).