The result enabled the Tigers to climb above their hosts, who lost at home in the Sky Bet Championship for just the third time this season.
Irvine gave the visitors the lead before getting the final touch after a goal-line scramble with 10 minutes to play after Alan Browne had brought North End level.
Nigel Adkins’ side could have been ahead much earlier, before Irvine’s 28th minute goal.
Kamil Grosicki raced through with Fraizer Campbell in support but his chip sailed wide in the third minute.
Preston were lacking options up front with five of their first-team strikers ruled out with injuries, leaving Lukas Nmecha as their sole man up front.
The 20-year-old had the hosts’ first opportunity but failed to hit the target as his header drifted over.
Midfielder Paul Gallagher had the closest chance when the Deepdale crowd gasped after his drive was tipped wide by Hull goalkeeper David Marshall, three minutes before Preston fell behind.
Hull’s Stephen Kingsley wriggled free to loft a high ball into the middle of the box, where Irvine stormed forward to head home powerfully and give his side the half-time advantage.
But parity was restored almost instantly after the restart when Browne’s spectacular hit-and-hope strike sailed into the top-right corner from outside of the area.
The equaliser sparked the home side into life and they pressed forward as Gallagher missed another chance. Daniel Johnson then sprinted at the Hull defence and had his shot blocked by a wall of Tigers.
Substitute Ryan Ledson, who came on after the break, saw his first shot of the match roll wide of the far post after 54 minutes.
Nmecha then leapt acrobatically in the box to attempt an overhead kick but could not trouble Marshall in the Hull net.
Five minutes later, Hull goalscorer Irvine screamed at referee Scott Duncan after he was brought down in the box and his penalty appeal was waved away.
The Tigers were knocking on the door for victory after Campbell and Grosicki both misfired their efforts on goal, and it was Irvine who stole it for Adkins’ side as he got the deciding touch to a Tommy Elphick corner.
The Preston defence desperately tried to clear their lines amongst a scramble but Irvine snuck in at the far post to steal the three points.