The Frenchman scored his 14th and 15th goals of the season - and could have been celebrating a hat-trick but for a missed penalty on the stroke of half-time.
Saha's salvo was the perfect antidote for the post-derby Blues and gave Everton a thoroughly merited victory.
Florent Malouda drilled the visitors ahead after 17 minutes, before Saha thundered a header past Cech to level.
The Frenchman then shot too close to Cech after Donovan had been tripped by Carvalho but made up for it with a stunning chest down and volley 15 minutes from time.
It was a stunning response from the Blues after Saturday's derby disappointment and a rocking Goodison Park roared their side off at the final whistle.
With Marouane Fellaini still awaiting a specialists' verdict on his ankle injured in Saturday's demolition derby and Steven Pienaar suspended, David Moyes was forced to make two changes to his starting line-up.
Mikel Arteta made his first start for almost a year and Diniyar Bilyaletdinov started for the first time since the FA Cup defeat by Birmingham last month.
Arteta lasted 75 minutes and was increasingly influential as the match wore on.
John Terry, predictably, was booed by a handful of fans - presumably active campaigners for the Sanctity of Marriage Bureau - but it was a token effort and hardly deflected the former England skipper from his game.
In fact the opening exchanges were tepid, Frank Lampard fizzing a firm drive a yard wide after seven minutes the
only meaningful goalmouth action.
That all changed after 17 minutes.
Petr Cech's long clearance was straightforward enough, but Phil Neville fatally stepped forward to shove Drogba in
a folorn bid to put the muscular striker off his header. The Ivorian simply cushioned a header behind him to the man
Neville had left, Florent Malouda, who crashed the ball past Howard.
The early strike allowed Chelsea to sitdeep, trying to lure Everton out of their own half and chisel further
openings in the Blues' back four, but the home side seemed reluctant to comply.
After 27 minutes Bilyaletdinov's first time cross from the left was met on the run by Leighton Baines dashing into
the Chelsea penalty box, but his first time volley flew straight at Cech.
But the effort seemed to rouse the Blues and they forced a couple of corners, the second of which produced a
glorious headed equaliser.
Landon Donovan's corner, from the Blues' right, was curled away from Cech and Louis Saha met it on the run to lose
his marker, John Terry, and bury a thunderous header past Cech.
Two minutes later Leon Osman went close with a rising 20-yard drive as Everton started to up the tempo.