Late goals from Steven Gerrard and Xabi Alonso gave Rafael Benitez's side their first back-to-back Premiership victories of the season.
Gerrard calmly slotted home a penalty on 85 minutes after substitute Peter Crouch was fouled by Liam Ridgewell.
Four minutes later, Xabi Alonso cracked in a shot that Villa keeper Thomas Sorensen probably should have kept out.
Prior to his fumble, Sorensen had kept Liverpool at bay, making notable saves from Djibril Cisse and Gerrard.
Prior to those late goals the game had looked to be heading for a draw, because of a combination of Sorensen's goalkeeping and Liverpool's indifferent finishing.
Just before winning the penalty Crouch missed the game's best chance with a poorly-placed header, while Cisse and Fernando Morientes had subdued matches.
Villa were just as indifferent in attack and Milan Baros had a quiet game against his old club.
Baros was superbly tackled by Jamie Carragher in the first half, while he was robbed of the ball by Alonso on 67 minutes when in a good position.
Liverpool have struggled badly for goals this season in the Premiership and in the first-half there was plenty of evidence of their misfiring attack.
Despite starting in the centre, Cisse was quickly instructed to play on the right wing, a position he looked clearly uncomfortable in.
Morientes looked just as out of sorts and he managed just one shot in the entire game, an effort comfortably saved by Sorensen.
Midway through the second half the Spaniard was replaced by former Villa striker Crouch.
The England striker quickly made his presence felt, picking out Gerrard, whose rasping shot was saved by Sorensen.
Liverpool fans will be wondering quite why it took them 85 minutes to find a way past Sorensen.
Early on, after an elaborate Liverpool move the ball arrived at Luis Garcia's feet, the Spaniard turned quickly and sent in a shot that went narrowly wide.
Cisse was the next to probe Villa's defence, slipping the ball to Gerrard, whose cross was blocked by Ridgewell.
Having weathered that early storm Villa came back into the game.
Baros was stopped in his tracks by a well-timed Carragher tackle, while Kevin Phillips flashed a header past the post.
The best chance of the first half fell to Cisse when Gerrard's raking pass released the Frenchman.
Cisse quickly controlled the ball but his shot was well saved by Sorensen.
The Frenchman made amends for his miss when he robbed Gareth Barry of possession only for his cross to elude Morientes and Garcia.
Finally, with five minutes to go, Crouch and Ridgewell tangled in the box and to the Villa defender's disbelief, referee Steve Bennett awarded the penalty.
Four minutes later the ball broke to Alonso on the edge of the box and the Spanish midfielder's swerving shot found its way past Sorensen.
Aston Villa manager David O'Leary:
"I am not happy with the penalty. It was a bad decision.
"You are going to have 100 penalties every game if you award them for those type of challenges.
"The referee couldn't wait to give certain decisions in favour of their big players. There is no doubt that the penalty changed the whole game."
Liverpool boss Rafael Benitez on under-pressure hitman Peter Crouch:
"People keep asking me about Peter's failure to score but I say many times that if he plays well and we win, it is enough.
"He has done a very good job for us and definitely gives us more options and alternatives in attack.
"Of course, he will be more confident if he scores but if he plays as well as he did against Villa I will be happy."
Aston Villa: Sorensen, Delaney, Mellberg, Ridgewell, Barry, Davis, McCann, Bakke (Hendrie 82), Milner, Baros, Phillips (Angel 61).
Subs Not Used: Samuel, Taylor, Moore.
Booked: Barry, McCann.
Liverpool: Reina, Finnan, Hyypia, Carragher, Riise, Gerrard, Alonso, Sissoko, Luis Garcia (Zenden 57), Morientes (Crouch 68), Cisse (Kewell 76).
Subs Not Used: Dudek, Warnock.
Booked: Sissoko, Alonso.
Goals: Gerrard 85 pen, Alonso 89.
Ref: S Bennett (Kent).