Vardy has led the scoring charts for much of the campaign, but a calf injury and a loss of form coincided with a tough stretch for Brendan Rodgers's third-placed Leicester.
However, Villa – second from bottom and facing swift relegation back to the Championship – made for an easy target at the King Power Stadium, granting the Foxes revenge for their EFL Cup semi-final defeat.
Harvey Barnes preyed on an awful Pepe Reina error to net the 40th-minute opener after a wasteful Leicester start, beating the goalkeeper to a long ball 25 yards from goal, steadying himself and firing beyond a pair of backtracking Villa defenders.
Vardy was introduced from the bench just before the hour-mark and had his name on the scoresheet four minutes later, as he dispatched a penalty after Tyrone Mings was adjudged to have handled in the area.
The former England striker doubled his tally with a near-post finish past Reina 11 minutes from time, and there was still time for Barnes to also convert a second, sweeping in Marc Albrighton's centre.
Dean Smith's Villa, beaten by Manchester City in last weekend's EFL Cup final, is two points from safety but has a game in hand.