Shane Long bundled home his second league goal of the season on eight minutes after he was the benefactor of Moussa Djenepo’s cross, which was smartly delivered with the outside of the boot.
Southampton, who managed 28 attempts with nine on target, twice came close to doubling their lead before the 90 minutes had come up. Jack Stephens poked the ball over the bar from in tight, before Pierre Emile-Hojbjerg forced a save with a tremendous left-footed volley.
Aston Villa only put one shot on target whilst taking just four, as their hopes for top-flight survival took a hit with 11 games remaining.
James Ward-Prowse, who deputised at right back for the injured Kyle Walker-Peters, did a superb job against Jack Grealish, and he thwarted a late attack from Villa in added time.
Stuart Armstrong would dispell any late drama when he raced onto Che Adam’s long ball before sliding the ball into the back of the net.
Southampton: McCarthy, Bertrand, Bednarek, Stephens, Ward-Prowse, Djenepo, Hojbjerg, Smallbone (Romeu 80), Armstrong, Ings (Adams 73), Long (Obafemi 73)
Unused subs: Gunn (GK), Vestergaard, Valery, Boufal
Goals: Long (8)
Aston Villa: Reina, Hause, Mings, Konsa (Hourihane 59), Targett, Douglas Luiz, Nakamba (Baston 81), Guilbert, Grealish, El-Ghazi (Trézéguet 28), Samatta
Unused subs: Nyland (GK), Drinkwater, Elmohamady, Engels
Bookings: Konsa (45+4), Reina (72)