The Rugby Park outfit took a huge stride towards securing their top-flight status as Lafferty's 11-minute first-half treble secured a 3-0 win over Dundee United.
The Northern Ireland international opened the scoring after 32 minutes, doubled their advantage three minutes later and then completed his hat-trick from the penalty spot after 43 minutes.
This was a vital victory for Tommy Wright's charges as it moved them five points clear of bottom club Hamilton with just three games remaining.
Crucially the win lifted the Rugby Park outfit out of the relegation play-off spot and two points above Ross County into 10th place.
Lafferty has proved to be an important signing for Kilmarnock in their bid to beat the drop as his hat-trick took his goal tally to 10 since joining the club in February.
Kilmarnock made four changes to the side which defeated Montrose on Saturday as they looked to strengthen their Scottish Premiership survival bid.
Dundee United, who are safe from relegation, rang the changes with manager Micky Mellon making seven to the side which progressed past Forfar in the Scottish Cup into Sunday's quarter-final encounter with Aberdeen.
Following a lacklustre opening from both sides, Kilmarnock made the crucial breakthrough through Lafferty after 32 minutes.
Ross Millen whipped in a glorious cross which Dundee United goalkeeper Deniz Mehmet came for but got nowhere near and Lafferty had the simple task of heading into the unguarded net.
It got even better for Kilmarnock just three minutes later as Lafferty notched their second as he was once again set up by Millen.
Chris Burke slid a through ball inside Dundee United full-back Jamie Robson to Kilmarnock's left-back Millen to race onto and he put a cut-back on a plate for Lafferty to lash the ball home from 10 yards out.
Lafferty was then gifted an opportunity to complete his hat-trick when Kilmarnock were awarded a penalty just three minutes before the interval.
From 12 yards out Lafferty made no mistake as he calmly sent Mehmet the wrong way to complete an 11-minute hat-trick.
Dundee United needed a reaction in the second half and substitute Archie Meekison, who had replaced Florent Hoti on the hour mark, came close to reducing the deficit as he unleashed a dipping drive which narrowly missed the top corner.
Meekison then played a through ball for Luke Bolton but he was denied by Kilmarnock goalkeeper Colin Doyle.
In the closing stages Dundee United's Adrian Sporle spurned a chance when clean through on goal and when Doyle fumbled the ball Louis Appere saw an effort blocked on the goalline.