Aston Villa started the day in 17th, one place above Southampton, separated only by goal difference, but they were hit by an early injury blow.
John McGinn had to be replaced by Marvelous Nakamba on eight minutes and that had a detrimental impact on the hosts.
Ralph Hasenhuttl set his men up to soak up pressure and play on the counter – an approach that worked fantastically well.
The opening goal came on the break when Nathan Redmond lobbed the ball over the top for Shane Long.
The Republic of Ireland striker’s shot was parried by Tom Heaton but Ings followed on to stab home the rebound for his 10th of the season.
Saints were 2-0 up by the break courtesy of Jack Stephens’ header from James Ward-Prowse’s corner as Villa lacked creativity.
The contest was over early in the second half when Ings pounced on a loose ball in the box before smashing home left-footed.
Dean Smith changed shape with the introduction of Jonathan Kodjia and Villa started to find a few openings.
They did pull one back through Jack Grealish, who volleyed home after a poor clearance from a corner, but ultimately didn’t have enough to mount a full comeback.
It’s Southampton’s first away league win since September 14 when they beat another newly-promoted side – Sheffield United.