The striker netted all four goals in a 4-0 defeat for Ayr that could have been far heftier were it not for the superb form of United goalkeeper Mark McGeown.
Ayr's attempts at retaining the trophy got off to the worst possible start and never recovered as the SPL side dominated from start to finish.
Less than two minutes were on the clock when the United defence failed to clear a Peter Leven free-kick, with McGeown and Martyn Campbell getting in a tangle before Boyd poked home the loose ball from three yards.
But Ayr should have levelled just seconds later with their only real chance of the game when Alan Combe's clearance was scuffed straight to Ian Cashmore but he sent his shot into the legs of the relieved keeper.
It was all one way traffic from there and Killie's threat down both wings had Ayr constantly on the backfoot.
Paul Di Giacomo showed just one example of that when he skinned the United defence in the 11th minute before seeing his powerful shot well saved by McGeown.
But the second goal didn't take long to arrive and it was simple stuff as Boyd headed home from a Colin Nish flick-on. Both strikers rose unmarked.
Ayr were reduced to fanciful efforts and John Nolan deserved credit at least for attemtping to catch out Combe with a 35 yard strike which dipped over.
But it was 3-0 before the break as another simple move carved open the Ayr defence with Boyd heading home a Leven cross to complete his hat-trick.
The half-time interval did little to turn the tide and Ayr were pinned further and further back as the game progressed.
It should have been 4-0 just nine minutes after the restart when Stevie Murray turned defence into attack down the left and crossed for the unmakred Nish who side-footed embarassingly wide from six yards.
Three minutes later, Di Giacomo and Boyd combined to set-up Nish with only McGeown to beat but he fluffed his shot straight at the United keeper.
McGeown then pulled off a brilliant stop to deny Murray on the rebound and then thwarted Boyd's follow-up effort.
The Ayr defence was all at sea as Killie raided forward at will and Canadian internationalist Rhian Dodds became the latest man to find McGeown in imperious form when his turn and shot was well blocked by the ex-Airdrie man.
The fourth goal was only a matter of time and Di Giacomo came oh so close in the 62nd minute when he cut inside and rifled a fine effort off the underside of the bar but luckily for Ayr the ball bounced just the right side of the line and was cleared to safety.
Di Giacomo then split the Ayr defence when he sent Boyd clean through but with the hitman looking odds-on to score again, he couldn't find a way past that man McGeown who pulled off yet another good save.
However, it delayed the inevitable for just 60 seconds before Paul Hyslop hauled down Murray in the box and Boyd stepped up to convert the penalty.
Thankfully that brought something of a ceasefire to the Killie attack and they slowed down through the gears as the game drew to a close.
Sub Stephen Naismith almost rubbed salt into the wounds, though, but he sent a lobbed effort just wide of the target with seconds remaining.
AYR: McGeown, McKinstry, Essler, McLaughlin, Campbell, Logan (Ramsay 80), Hyslop (Strain 70), Nolan (Casey 46), Varielle (Reid 70), Maisano (Wardlaw 46), Cashmore (Robertson 80). Unused sub: Hutton.
KILMARNOCK: Combe, Fowler, Hay (Dillon 80), Dodds (Wright 90), Greer, Leven (Johnston 70), McDonald (Locke 80), Di Giacomo, Boyd (Invincible 80), Nish (Naismith 70), Murray. Unused sub: Smith.
Referee: Iain Brines; Crowd: 3,885
Thanks to the Official website for the match report.