Their struggle against relegation has been largely overshadowed by the confirmation of the death of their striker Emiliano Sala, whose body was this week recovered from the crashed plane that had been taking him to Cardiff, and they paid him the ultimate tribute by securing three important points.
Victory crucially takes Cardiff out of the bottom three and above Southampton, who had been undefeated in the top flight since the turn of the year under their new manager Ralph Hasenhuttl.
It also ensured successive top-flight victories for the Bluebirds for the first time since April 1962, and came after the hosts had already pulled level in stoppage time.
It had taken 38 minutes before either team, perhaps influenced by the emotion and tension of the occasion, registered a shot on target, let alone threatened to score.
After a minute's silence in honour of the late Sala, both began with significant tempo but without creativity.
That they both remain at risk of relegation no doubt contributed to the uninspiring balance that had existed between them until Pierre-Emile Hojbjerg produced that first strike on goal.
After chesting a loose ball towards the edge of the area and shooting towards the near post, he watched as the diving Neil Etheridge saved and then as his team-mates responded with greater intent.
Jan Bednarek attempted a through-ball towards Nathan Redmond that was routinely collected by Etheridge, and then Redmond played a one-two with Hojbjerg before sending a low cross towards goal that was deflected by Sol Bamba into the goalkeeper's hands.
An effort early into the second half from the hosts' Yan Valery, who worked his way into the area and created space before shooting straight at Etheridge, furthered Southampton's momentum, and Cardiff responded by introducing Zohore and Leandro Bacuna to ease the growing pressure.
Harry Arter led one attack down the left that came to little, but in the 69th minute after winning a left-wing corner the visitors unexpectedly took the lead.
When Joe Ralls crossed into the penalty area, Callum Patterson headed on towards Bamba, and from directly in front of goal the club captain stretched his right foot to reach the loose ball and poke it beyond the diving Alex McCarthy and in.
Bacuna swiftly tested McCarthy with another effort, struck powerfully from 25 yards as the goalkeeper parried wide, and Southampton were then denied a deserved equalising goal.
When Valery ran into the area and forced a fine save from Etheridge, Charlie Austin's rebound was blocked by Lee Peltier to Mohamed Elyounoussi, who also struck before also watching Peltier block.
It was in the first minute of stoppage time that Southampton appeared to have secured a draw. James Ward-Prowse's corner was headed by Austin towards the back post, from where the unmarked Jack Stephens seamlessly finished.
After two further minutes and following another attack with both teams stretched, Arter's misplaced shot fell to Victor Camarasa, who fed Zohore before watching the striker finish from close range and inside the far right post to secure all three points.