Sebastien Haller and Michail Antonio also got on the scoresheet as the Hammers saw off an ineffective Southampton side that lacked creativity and a killer instinct in front of goal.
Story of the match
The first chance of the game was created by the hosts on the counter-attack after 12 minutes when Michail Antonio broke away, but he was unable to play through Jarrod Bowen, and a promising attack went to waste.
However, it didn’t take long for West Ham’s January signing to get another opportunity, and this time he converted, Bowen chipping over Alex McCarthy to make it 1-0 after he was assisted by Pablo Fornals’ incisive pass.
Southampton looked flustered after the Hammers’ opener and Sebastien Haller came close to doubling the home side’s advantage moments later, McCarthy with a solid stop to deny the forward from close-range.
The away side struggled to create in the opening 45 minutes, however they executed a superb flowing counter-attack of their own to equalise after half an hour, James Ward-Prowse cutting it back to Michael Obafemi who finished well inside the box.
The goals kept coming during an eventful first-half and West Ham regained the lead shortly before the interval through Haller, the Frenchman demonstrating his aerial prowess to beat McCarthy in the air before finishing at a tight angle.
The Saints started on the front foot after the break and brought on talisman Danny Ings, however they failed to take their chances and found themselves 3-1 down when Antonio smashed home following Fornals' lofted pass.
It almost got worse on 60 minutes as Haller played his strike partner through on goal again with an outrageous rabona pass, but a good saved denied Antonio a second.
With their two-goal advantage West Ham looked to hold on for a vital win, and the whole team had to dig in deep as Southampton drove forwards looking for a dramatic comeback.
There were very few significant chances in the game's closing stages as David Moyes' men protected their lead, and despite showing intent, Ralph Hassenhuttl's team seemed to lack creativity as they tried to overturn the deficit.
Ward-Prowse attempted to pull one back with a few late set-pieces, but he wasn't able to trouble Lukasz Fabianski and West Ham held on for all three points.
Takeaways from the match
Bowen bags on Hammers home debut
Jarrod Bowen made an immediate impact in Claret and Blue as he got his first West Ham goal, helping his new side to victory.
The January signing from Hull City was energetic all afternoon, getting supporters off their seats with his contributions at both ends of the pitch, and he could play a vital part in West Ham's bid to avoid relegation.
Important result in the relegation battle
Southampton look to be safe enough to avoid the drop, however West Ham are still amidst a relegation battle despite their win.
A vital three points moves the Hammers out of the relegation zone, but they are still only two points clear of Aston Villa in 18th, and will need to use the hard-fought win as momentum for the rest of the season.
West Ham fans protest against board
Before the game there was a protest held by a large number of West Ham fans against the club’s ownership under David Gold, David Sullivan and Karren Brady.
At least 3000 supporters took part in a peaceful march along Newham Greenway, displaying ‘GSB OUT’ flags and banners, before making their way inside the London Stadium to support the team.