West Ham secured their best league finish in 22 years and qualified for the Europa League as a 3-0 win over Southampton secured a sixth-placed finish.
In front of 10,000 fans, David Moyes' side needed just a point to secure sixth place and took full control of their destiny in the first half with Pablo Fornals scoring twice in a quickfire double (30 & 33) that took the game away from Saints.
Declan Rice added further gloss to the scoreline in the closing stages (86).
It caps a memorable season for Moyes and his impressive side, whose haul of 65 points sets a new club record for most points in a Premier League season.
They have qualified for the Europa League group stage, courtesy of Leicester winning FA Cup, while Southampton end a rather mediocre season in 15th.
- Premier League table | Results
- How the teams lined up | Match stats
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West Ham: Fabianski (8), Coufal (8), Dawson (8), Ogbonna (7), Cresswell (7), Soucek (7), Rice (8), Fornals (8), Lingard (7), Bowen (7), Antonio (7)
Subs used: Benrahma (7)
Saints: McCarthy (5), Walker-Peters (7), Bednarek (6), Vestergaard (6), Salisu (6), Minamino (6), Ward-Prowse (7), Armstrong (7), Diallo (6), Ings (6), Redmond (6)
Subs used: Tella (6), Romeu (6)
Man of the match: Declan Rice
How West Ham got the job done…
West Ham's permutations for a top-six finish, were simple. Avoid defeat and they would finish sixth.
Despite their destiny being in their own hands, there were a few early nerves as Saints started with their usual gusto. A swift counter-attack ended with Takumi Minamino sprinting through on goal but his chipped finish spun inches wide of the far post.
Lukasz Fabianski then had to earn his keep with a brilliant blocked save to divert a Kyle Walker-Peters effort from a tight angle around the post.
- Lukasz Fabianski was passed fit for their most important game of the season. He was one of two changes from the win at West Brom with Said Benrahma dropping out in place of Jarrod Bowen.
- Danny Ings, Nathan Redmond, Jan Bednarek, Ibrahim Diallo and Takumi Minamino all returned for Saints.
That seemed to spark the Hammers into life and Fornals edged them ahead with their first real meaningful effort on goal. Jarrod Bowen let fly from the angle and Alex McCarthy could only palm his save straight to the onrushing Fornals, who smashed home from close range.
The London Stadium was now alive with noise as their players responded by keeping Saints pushed back and the second goal duly came.
The brilliant Vladimir Coufal joined the attack down the right and delivered his usual level of quality into the danger zone. Fornals was lurking with intent and managed to sweep another sharp finish beyond McCarthy to ease any tension that was lingering within the home ranks.
With nothing on the line for Southampton, the second half was played out in a professional manner by the Hammers. Fabianski was called upon to make a flying save to deny Jan Bednarek from a wicked James Ward-Prowse delivery but led by Craig Dawson, the West Ham backline never looked like being breached.
There was still time for one more moment of celebration for the home fans when Rice scampered through on goal down the left. The Southampton defence was nowhere to be seen and Rice took advantage, firing home from close range.
West Ham are going on a European adventure.
Man of the match: Declan Rice
A huge summer beckons for West Ham's skipper. Not only is he likely to be the driving force for England in central midfield at the European Championships, but he's also got some big decisions to make regarding his future.
Yet again he dominated a Premier League match from his position in front of the back four, making the right passes at the right time and breaking up play when it looked like Southampton were making waves.
No one gained possession more for their side than Rice did (7). West Ham will be playing Europa League next season but they have a player of Champions League standard within their ranks. They have a job on to keep hold of him.
What the managers said
West Ham boss David Moyes: "I think it's a huge achievement from where we came from. It's the biggest step the club has ever made - to jump this far is incredible. We are in a really good place at the moment.
"I think the players have been remarkable, we have grown as a team and got better and we are in a really good place at the moment. We have to take it on again and keep up the standards we have set. If I have the exact same group of players next season I think we can continue to be successful. I am hoping we can add similar characters to the squad next season."
Southampton boss Ralph Hasenhuttl: "This is the story of our season, we create the chances and they score the first goal. We gave it away. It's not important to speak about us today, congratulations to West Ham for reaching Europe.
"They deserved to win today. Our defending was not Premier League-like and we have to change it massively otherwise it will be about relegation. We conceded the second most goals in the Premier League this season and the way we conceded today was a mirror of everything we've seen. It's very frustrating. It's a reality check of what we can achieve. We deserved to finish in 15th."
- West Ham United secured a top-six finish in the Premier League for only the second time, with the Hammers also finishing 5th in 1998-99 under Harry Redknapp. 2020-21 was manager David Moyes' best finish since he came 6th in his final season as Everton boss in 2012-13.
- Southampton have lost 10 of their 11 Premier League away games in 2021, conceding 33 goals in these 10 defeats, scoring just seven in return.
- Southampton have conceded more Premier League goals in 2020-21 (68) than they have in any other season in the competition.
- West Ham have won 19 Premier League games this season - their highest tally of wins in a single top-flight campaign since 1985-86 when they finished third (26 wins in a 42-game season).
- Only West Ham teammate Aaron Cresswell (8) has more assists amongst defenders in the Premier League this season than Vladimir Coufal (7).
- West Ham's Pablo Fornals has scored five goals in the Premier League this season (33 apps), three more than he netted in 2019-20, despite playing three fewer games (36 apps).
What's next? Euros, transfer window, 2021/22 key dates
Euro 2020 kicks off on Friday June 11 - just 19 days after the conclusion of the 2020/21 Premier League season - and runs until Sunday July 11.
The 2021/22 Premier League campaign will start on the weekend of Saturday August 14 - 34 days after that Euro 2020 final at Wembley.
Clubs will be able to start planning for the new term when the top-flight fixtures are released at 9am on Wednesday, June 16 but transfer business can start in earnest before then, with the summer transfer window opening on Wednesday June 9.
- 2021/22 season - all the key dates
- 2021/22 fixture release dates
- Summer transfer window 2021 - what you need to know
- Premier League kits for 2021/22
- Euro 2020 - full fixtures and schedule
The 2021/22 Championship season begins a week before the top-flight one on the weekend of Saturday August 7. All Sky Bet EFL fixtures will be announced at 9am on Thursday June 24.