Tenth-placed Preston, whose lingering play-off aspirations were snuffed out by QPR nine days earlier, made the Foxes work hard for their first-half chances as they tried to avoid having the Championship trophy hoisted by Leicester at Deepdale.
Preston goalkeeper Freddie Woodman rushed off his line to deny Vardy, then saved well again soon after to foil McAteer, who went on to squander a huge headed chance from close range just before the half-hour mark.
Leicester’s leading scorer Vardy eventually gave the visitors a deserved lead with a scuffed first-time finish as he swivelled on to a Yunus Akgun cutback to find the bottom corner.
When he pounced for his second early in the second half, smashing the rebound home after Wout Faes crashed a shot off the post, Vardy had the visiting fans joyously celebrating a coronation party.
In his 12 years with Leicester, Vardy has now scored 190 goals in 463 appearances.
The striker was there 10 years ago when they last won promotion and the Championship title and, after symbolising all the success that followed, he returned with the Foxes to the second tier once more.
His dominant presence and goals have been vital in returning Premier League football to King Power Stadium but with the striker out of contract in the summer, the value of his continued presence will undoubtedly be emotively debated in the coming weeks.
"Jamie has always scored goals in his life and he will score goals always," said Foxes boss Maresca.
"He has helped us a lot this season on and off the pitch - him, Marc Albrighton, Conor Coady, Jannik Vestergaard and all the experienced players."
It took a smart save from Woodman to deny Vardy a memorable hat-trick, but McAteer did make it 3-0 soon after as he nodded home after being found unmarked by Abdul Fatawu – who then went on to hit the woodwork in search of a fourth.