To help Leeds break a string of back-to-back defeats to stretch Southampton’s winless run to a much more troubling eight matches, Patrick Bamford scored his 13th goal of the season.
The striker scored early in the second half, timing his run to perfection to beat offside and lock on to Tyler Roberts’ through-ball before firing a low shot into the far corner.
The points were sealed from the box’s edge with a tidy Stuart Dallas end and Raphinha’s excellent free-kick. Before the opener, Leeds had been largely on the back foot, with Jan Vestergaard and Nathan Tella spurning the Saints’ good early chances, who were also aggrieved by two refereeing decisions.
The first was a penalty awarded on the pitch but correctly overruled by VAR after Tella went down in the net, suggesting the forward-kicked defender Diego Llorente and not the other way round.
They were more disappointed that a free-kick was ruled out and Che Adams finished easily, with Andre Marriner showing that he had not blown his whistle to start playing again.
The home side may have all-but wrapped up the points five minutes after the opener, but before Bamford saw a shot well-saved by Alex McCarthy, Roberts fired inches wide.
To avoid Llorente scoring his first Leeds goal from near range, the Saints goalkeeper also saved brilliantly with his foot.
Danny Ings started on the Saints’ bench and was introduced to little effect with half an hour to play.
Oriol Romeu, who had previously stopped shooting Raphinha after he had broken free with a genius sliding tackle to rub salt in the wounds of the visitor, added by limping off to his side’s injury problems.
The win takes Leeds up to 10th in the league with 35 points from their 25 matches. Southampton is five points worse off than Fulham, whose shape picked up when the Saints were collapsing, just eight points down.