The visitors from London were dominated from start to finish by a Toffees side who have been rejuvenated by their acquisitions during the January transfer window
The Toffees opened the scoring just five minutes in thanks to the returning Steven Pienaar's wonderfully controlled strike.
They then pinned Chelsea back with some brilliantly incisive attacking and got a deserved second through Denis Stracqualursi to follow up their win over Manchester City with another impressive victory.
The hosts made just one change to the side which was held to a frustrating draw against Wigan, with captain Phil Neville replacing Tony Hibbert at right-back. New signing Nikica Jelavic failed to make his first start for the Toffees after coming down with a virus and Denis Stracqualursi was thus charged with leading the line for the second game in a row.
For the visitors, Gary Cahill was the man to pay for the defensive struggles against Manchester United as the January signing was replaced by Branislav Ivanovic in the middle, with Jose Bosingwa coming in at right-back. Elsewhere, Frank Lampard made his return to central midfield as Florent Malouda dropped to the bench.
Given that Everton had beaten the league leaders at Goodison Park in their last home game, it was unsurprising they started full of confidence and somewhat caught Chelsea on their heels. The visitors looked shaky defensively and paid the biggest price just five minutes in as Everton took the lead.
A coming together between Tim Cahill and Lampard saw the ball loop over the Blues’ defence and fortuitously into the path of Pienaar who controlled brilliantly on his chest and smashed beyond Petr Cech.
Despite the nature of the goal, it was no more than the hosts deserved and they almost added to it just moments later as a Neville cross was met by the head of Stracqualursi, who nodded inches wide of the post.
A Donovan drive from distance, which stung the palms of Cech, gave the hosts further hope of gaining a Premier League surprise, as Andre Villas-Boas’ men appeared rattled.
It took 25 minutes for the Londoners to show any sort of fight, but a chance for a Fernando Torres head at goal was brilliantly denied by Sylvain Distin before Daniel Sturridge saw his shot desperately blocked at the edge of the box.
Lampard then rolled wide from a similar distance to confirm Chelsea’s arrival in the match just early enough for them to perhaps make a go of salvaging a result.
Tim Howard’s flap at a cross from the right almost allowed Lampard in again shortly agter before a Leighton Baines free-kick was equally poorly dealt with by Cech at the other end, the Czech shot stopper being let off with the linesman’s flag indicating Cahill’s offside position.
A wild kick from a frustrated Raul Meireles on the breaking Stracqualursi conveyed Chelsea’s frustrations in the first-half, but the hosts failed to capitalise by wasting the free-kick, taking it short.
A Torres header from close range was then easily collected by Howard as an entertaining first period was brought to a close with Everton leading.
The pace did not appear to have slowed as the second half commenced, with both sides continuing to show the attacking intent which had made the first period so good to watch.
A Pienaar-led Everton break, after Torres’ wasteful control at the other end, saw the South African buy a free-kick brilliantly. Unfortunately for the hosts, a rare poor delivery from Baines could not beat the wall but the endeavour to win the set-piece proved they had little to fear from a side who are chasing European football next term.
Stracqualursi’s twist and turn in the box moments later ended in a blocked shot but emphasised Chelsea’s position as the side under the cosh from an Everton whose creativity has improved no end since a productive January.
Another weak Torres header from a deep cross served to underline Chelsea’s lack of attacking thrust and there appeared no way back into the game with Everton counter-punching brilliantly.
And it was to prove so as the Toffees landed the knockout blow with 15 minutes remaining on the clock. A brilliant run in off the right from Donovan found the Blues’ defence backpedalling, and the American’s wonderfully weighted pass allowed striker Stracqualursi to smash beyond Cech, despite the keeper getting a palm to the ball.
Chelsea's game was up with that goal and Villas-Boas appeared to know it, removing Mata - one of their few impressive performers - for youngster Romelu Lukaku.
Everton were then little troubled by their visitors, as they had in truth been throughout the match, and kept the ball patiently in order to see out a deserved win which may mark yet another late-season renaissance.