Essex 76 (Abbott 6-20) and 362 (Lawrence 101, Bopara 57) beat Hampshire 254 (Bailey 89, Vince 60, Porter 4-53, Harmer 3-47) and 76 (Cook 5-18) by 108 runs
Sam Cook took a maiden first class five wicket haul as champions Essex pulled off an extraordinary 108-run victory despite earlier being forced to follow-on against Hampshire.
Fast bowler Cook blasted through Hampshire's top order to end with figures of five for 18, and leave the relegation threatened home side with their lowest total since 1984 - as they were bowled out for 76.
It was the first time since 1999, when they beat Nottinghamshire, that Essex managed to win a Specsavers County Championship match after being asked to follow-on.
Incidentally, the previous occasion, the second of three in their history, was also against Hampshire, at Bournemouth's Dean Park, in their last Championship winning campaign 25 years ago.
Cook revealed that coach Chris Silverwood had invoked the spirit of that victory when Essex were at their lowest.
"It is an amazing environment to thrive in with everyone so happy after winning the Championship," he said.
"Silvers talked about the 1992 following on win against Hampshire in the dressing room a few days ago when we were a few wickets down and looking down in the dumps.
"He said 'this happened 25 years ago, why can't it happen again?' and it just sums up our season as a whole that history has repeated itself."
Hampshire, who had bowled Essex out for 76 in the first innings, had been set 185 runs to win - after Neil Wagner and James Foster's 82 run partnership for the eighth wicket put the wheels in motion for the remarkable win.
Hampshire's pursuit started poorly as Joe Weatherley was pinned lbw as he walked across his stumps by Sam Cook in his first over. It got worse five overs later as Tom Alsop edged Jamie Porter behind.
Cook then deceived Jimmy Adams by coming around the wicket and wide of the crease to clatter a delivery into the left-hander's off stump.
The 20 year old, making just his third Championship appearance as he prepares for the final year of his history degree, then produced a wicked inswinger to bowl George Bailey. Hampshire had lost three wickets without scoring a run as they were stuck on 12.
Sean Ervine was lbw to Porter, his 70th scalp of the season, leaving the hosts 25 for 5. Vince, one of three batsmen to depart for 10, was next to fall as he was lbw to the rampant Cook.
Off spinner Simon Harmer entered the attack in the 21st over and struck with his first delivery as he bowled Liam Dawson with a vicious spinner - Hampshire now 37 for 7.
Wagner then grabbed two wickets as Gareth Berg edged to first slip and Kyle Abbott guided to cover point.
Cook completed the innings as Fidel Edwards edged behind, with Ian Holland unbeaten on an innings-high 16.
Starting the day just 69 runs ahead, Essex saw skipper Ryan ten Doeschate depart just six balls into the day as Edwards continued where he had left off on the previous evening by striking him on the pads.
Three balls into the next over Abbott produced an inswinging yorker to cartwheel nightwatchman Porter's middle stump.
Ian Holland grabbed the eighth Essex wicket by finding the edge of Harmer's dangling bat but Foster and Wagner then put on their useful stand to swing the game in Essex's favour for the first time.
New Zealander Wagner in particular swung his bat with gusto to find himself reaching an entertaining 44 - before one shot too many saw him caught on the midwicket boundary.
Foster was the last man to fall after a match-aware 47 before he was leg before to Abbott - his eighth wicket of the match.
But Hampshire's incredible collapse, which leaves them within touching distance above the relegation zone, made sure Essex remained unbeaten with the most unlikely of their nine wins this season.
Hampshire's head coach Craig White said: "We were hoping to chase a few less, maybe around 120-130 and it could have been difference, although that would have been tough the way they bowled.
"Everyone needs to take a look at themselves in the mirror and find out why we keep losing clumps of wickets. It needs addressing."