Despite dominating from the start of the match, the Saints had to wait until the 45th minute for Jay Rodriguez to open the scoring.
The hosts completed the emphatic win in the final minute of normal time when Rodriguez added his second of the afternoon.
Below, Sports Mole takes a closer look at Southampton's success over Newcastle.
On target: 11
On target: 2
Was the result fair?
Southampton deserved the win, there can be no argument to suggest otherwise. Mauricio Pochettino's side were the better side from the first minute, and they were barely caused a problem on their way to a comfortable triumph. Newcastle fans have been frustrated on a number of occasions this season, but few results will have hurt as much as this one.
The Saints were at their brilliant best. It was a vintage display from the hosts as they passed the ball with excellent accuracy throughout the first half, and they could have been further ahead. It looked like it could have been a difficult afternoon when Southampton missed a number of chances early on, but they went through the gears to score four times. The whole team performed impressively, but it was Lallana, James Ward-Prowse and Calum Chambers who were at the heart of most good things for the home side.
It was an awful afternoon for the travelling supporters, who had very little to cheer. There struggles to filled the void left by the injured Loic Remy continued as Newcastle lacked a cutting edge on the rare occasions they did break forward. A lot of faith was placed in Hatem Ben Arfa, but he enjoyed one of his poor afternoons and could have no complaints with being replaced at the break. They aren't the first side to struggle to handle Southampton's midfield, who passed the ball with apparent ease with very little pressure being applied in the middle of the pitch. A day to forget for the Magpies.
Sports Mole's man of the match
Adam Lallana: On another day, this award could have gone to Chambers, who was impressive in both attack and defence. However, Lallana produced a stunning display filled with clever runs and excellent passes, but his performance will be remembered for the 25-yard strike that left Elliot with no chance in the Newcastle goal.
Southampton didn't make too many mistakes in the win, but Lallana won't want to be reminded of his miss in the first half. The captain somehow managed to head wide from close range while in plenty of space. Luckily for the England international, it didn't make a difference to the final result.
Plenty of eyes were on Andre Marriner following his horror show at Stamford Bridge last weekend. The referee possibly should have shown a red card to Papiss Cisse in the second half after the striker lunged in on Chambers.
Southampton: Pochettino's side return to action next Saturday against Manchester City.
Newcastle The Magpies will look to recover from this defeat when they Manchester United in a week.