On-loan Celtic defender Hooiveld powered home the winner on the stroke of half-time in front of a St Mary's record crowd of 32,150, but they were put under immense pressure by the Hammers, who hit the post late on through Mark Noble's cross-shot.
The visitors - with an unbeaten away record - started brightly, with Matt Taylor testing Kelvin Davis with a low drive inside the opening minute.
Saints' response came from returning skipper Dean Hammond who fizzed a shot over the crossbar from 30 yards and then tried his luck again from distance but with the same outcome shortly afterwards.
West Ham were forced to make an early substitution when Taylor limped off to be replaced by Frederic Piquionne with what looked to be a recurrence of a calf injury.
It was the home side who were on top as the half progressed. Richard Chaplow should have done better with a close-range volley.
The Hammers hit back as Piquionne sent John Carew clear down the left. He picked out captain Kevin Nolan but his 22-yard curling shot flew inches past the upright.
Striker Sam Baldock, who scored his first goals for West Ham on Saturday, looked set to get his name on the scoresheet again in the 36th minute but his hooked effort from eight yards was well blocked by the legs of Davis.
That sparked Southampton back into life, and after David Connolly saw a first-time volley gathered by Manuel Almunia, they opened the scoring on the stroke of half-time.
Hammond's corner from the right picked out Hooiveld and the on-loan Celtic defender powered a header past the keeper.
It was the home side who bossed the opening stages of the second half, with a succession of corners ending with Winston Reid blazing over.
A Rickie Lambert free-kick was deflected wide for Saints and at the other end Baldock found himself one on one with Davis but sent his curling strike past the post as the game opened up.
A slip from Papa Bouba Diop allowed Connolly to race forward and bend a shot just wide, and the same player spurned another chance moments later.
Sam Allardyce's side continued to press, though, and a well-worked free-kick saw Nolan roll his marker and bring another good stop from Davis.
Chaplow was not too far away with an angled drive and Guly Do Prado curled an effort past the far post as Saints came back into it.
Guly was presented with another opportunity when a mix-up between George McCartney and Noble allowed Lambert to pick him out, but the Brazilian saw his shot blocked by Almunia.
In a frantic finish, Noble saw a free-kick tipped onto the roof of the net and from the resulting corner his cross flicked off the head of a defender and came back off the far post but Southampton held on to maintain their 100% home record.