Douglas Luiz tapped in from close range as Coutinho laid the chance on a plate for him, and went on to bag one himself just after the break following some dazzling footwork.
Ings then grabbed the fourth only minutes later, picking up a goal against his former club.
Story of the match
Villa started the game in a very narrow fashion as Southampton aimed to exploit them in wide areas.
However, it was the home side who scored first as Coutinho arced a ball into the feet of Ings.
The former Saints man slid Watkins in who swivelled around Jack Stephens and fired the ball past Forster for the opener.
Jacob Ramsey almost picked the lock in the away side's defence after catching them on the break.
He played through Ings who slipped as he tried to turn into space, but Southampton were incredibly fortunate to get away with that turnover.
Gerrard's side looked very organised out of possession, as they aimed to push the opposition as far back as possible.
Watkins had the opportunity for a second after 30 minutes, he was slid in by Coutinho.
However, the 26-year-old's finish was weak and saved comfortably by the feet of Forster.
Adams and Mohamed Elyounoussi then found themselves free at the back post following Livramento's cross but got in each other's way as the former headed over.
Romain Perraud was feeling confident after his midweek goal against the Hammers, he drilled a long-range effort just wide of the post.
Villa doubled their advantage not long before halftime, as Chambers lofted a ball into the area from the edge of the box.
He found Coutinho who beat the offside trap, the Brazillian then laid the ball down into Luiz's path, who struck home neatly.
Hassenhutl opted for a half-time change as Yann Valery replaced Elyounoussi at the break.
Villa continued to pile on the pressure in search of a third after the break and found it shortly after through Coutinho.
Seconds later, Matty Cash found himself in acres of space to cross, he cut the ball back to Ings, who stroked past the 'keeper for their fourth of the afternoon.
The Saints looked to be gaining some momentum as they saw a series of successive corners go their way, including an effort that saw Young forced to head over his own bar from close range.
Gerrard's side closed the game out with relative ease, as they continued to create chances and limit Southampton's possession on the ball.