David Moyes got the better of Sam Allardyce to ensure victory against his former club and sign off the season in style.
The Hammers were the superior side from the outset, with midfielder Manuel Lanzini taking advantage of sloppy Everton defending to open the scoring just before half-time.
Mark Arnautovic deservedly made it two with a wicked shot that deceived Jordan Pickford, before a moment of quality from Oumar Niasse halved the deficit.
But Man of the Match Lanzini's superb curler clinched three points for Moyes on what could well be his final game as manager at the London Stadium.
Here are four things we learned from the end of season clash.
Allardyce's attempt to match up hosts dramatically fails
If this was a battle of minds between two long-time Premier League managers then it was one that Sam Allardyce emphatically lost.
Not for the first time this season, the Everton manager mirrored the opposition in an attempt to negate their strengths. The problem was, though, that West Ham have been playing 3-5-2 for months and know the intricacies of the system far better than the Toffees. One week on the training ground was never going to be enough to create a level playing field at the London Stadium.
And so Everton chased shadows in the early stages in particular as they sought to get to grips with the change in formation. Links between defence, midfield and attack were few and far between as Manuel Lanzini and Marko Arnautovic ran riot.
As usual, Allardyce's problem was that he paid the opposition far too much respect. This was a side that had lost 4-0 at Goodison, after all, and the 63-year-old's sole ambition was to seemingly play for a point.
Even that, though, looked like a stretch on the evidence of a hugely disappointing first-half. Indeed, the opener for Lanzini saw West Ham take full advantage of flaws in Everton's system as Michael Keane and Phil Jagielka went AWOL. What was patently apparent was that the Blues defenders weren't familiar enough with the system to know who exactly was accountable.
With both managers appearing to be on their way out this summer, today was at least in part an opportunity to show what they can do to prospective new employers.
Few will have been impressed with the imperfect setup served up by Allardyce in east London - especially Everton major shareholder Farhad Moshiri.
Everton need their own Lanzini
There was a time over the summer when Everton were seemingly awash with Number 10s. As Gylfi Sigurdsson, Wayne Rooney and Davy Klaassen headed through the Goodison Park welcome doors, talk centred on how the Blues would accommodate the trio in Ronald Koeman's system.
Fast forward less than a year, and the dearth in creativity in Everton's ranks is now painfully apparent. With record signing Sigurdsson injured, Rooney apparently set for a summer exit and Klaassen having failed to make an impact, Blues supporters at the London Stadium saw their side give another performance lacking any semblance of ingenuity.
Unfortunately for Everton chiefs already under fire for a poor summer of recruitment, the situation was made even more stark by the success of Manuel Lanzini for Saturday's opponents.
Playing just off lone striker Marko Arnautovic, the Argentine's strong running and incisive passing caused havoc for an ill at odds visiting defence. The main standout in a dominant West Ham display, Everton could have been forgiven for casting envious glances at a player signed for a bargain fee of £9.4 million just two seasons ago.
Given their own high-profile flops, it was another reminder of just how flawed Everton's scattergun approach to recruitment has been over the past few seasons.
Allardyce's involvement at the club is quite evidently not the only thing that needs to change this summer.
Moyes finally emerges triumphant over former side
Before Saturday, it was six defeats in six for David Moyes against his former club. Hanging as a millstone around his neck, the dreadful run at one stage showed no sign of abating.
Yet with Everton drifting under Allardyce, the Scot took full advantage of the opportunity to put the unwanted record to bed.
In truth, for long spells there was only one outcome on the cards. The decision to push Marko Arnautovic forward into the lone striking role has paid dividends over the past few months as the Hammers secured their Premier League status - and the Austrian was again key here as he bullied Michael Keane in particular.
For that Moyes deserves at least some credit. Not so long ago, West Ham looked like relegation fodder in waiting. Not now.
To see Lanzini excelling behind the striker and Arnautovic now totally comfortable ahead of him is to know that the ex-Everton manager has, at the very least, stabilised the east London club before his expected summer departure. Here they looked more like a mid-table team than the one that had earlier appeared destined for the drop.
Reputation restored and records settled, signing off this way against his former side will have tasted particularly sweet for Moyes.
Change is afoot for both clubs as 2017-18 post-mortem begins
With both clubs safe from relegation heading into the final day, attention on Merseyside and east London had already switched to what comes next this summer.
In both cases, significant upheaval should probably be anticipated as the post-mortem begins in earnest.
For judging by the money over the last few seasons, both Everton and West Ham are drastically under-performing. Summer now offers an enticing opportunity to start to right the wrongs of previous campaigns.
What follows could well involve more than just managerial changes.
At Everton, Allardyce's predicted departure may be part of a mass overhaul that also sees substantial turnover on the playing staff and at boardroom level.
In the opposite dugout, it would also be a huge surprise if Moyes retains his job as West Ham manager.
Both sides have learned that money is not the solution to every Premier League hurdle, and must respond accordingly.
With disillusionment high, the first challenge for Everton and West Ham is to restore faith among their respective fanbases in the direction of travel.
And that, after this season, will be no mean feat.
