Saints skipper Adam Lallana and record signing Gaston Ramirez were on target at St Mary’s, with the injury-plagued visitors unable to provide any kind of attacking threat.
Nigel Adkins’ side looked the more likely to edge in front during a competitive first half, with Rickie Lambert crashing the angle of bar and post with one 25-yard free-kick.
Lallana went one better on 34 minutes, with Ramirez unselfishly squaring for him to roll into an empty net after Newcastle were left all over the place at the back.
The Saints then wrapped things up on the hour mark, with Tim Krul spilling a low cross from Jason Puncheon into the path of Ramirez to bundle home.
It could have been many more for the hosts, with the woodwork and match officials conspiring against them.
Puncheon thought he had grabbed the goal his lively display thoroughly deserved midway through the second half, but his low drive cannoned back off the base of the post.
Jose Fonte that hit the frame of the goal for a third time, with a towering header from the centre-half leaving Krul flapping at thin air.
Newcastle were offering little to suggest that Southampton would be made to pay for their inability to convert pressure into goals, with Pardew’s side severely, and worryingly, lacking in spark.
The Magpies survived one more scare late on, with substitute Jay Rodriguez rattling into the back of the net only to see a marginal offside call go against him.
Victory for the Saints, and just a second clean sheet of the season, sees them climb into 17th and they will be looking to make the most of the upcoming festive period to pull further of trouble.
Newcastle, meanwhile, have now suffered three straight defeats to slip into 14th spot and Pardew needs to find a winning formula from somewhere if an alarming slump is to be halted and pressure is to be prevented from mounting on his shoulders.