|Vitality Blast final, Edgbaston:|
|Worcestershire 145-9 (20 overs): Moeen 32, Wessels 31; Harmer 3-16|
|Essex 148-6 (20 overs): Bopara 36*, Westley 36; Moeen 2-22|
|Essex beat Worcestershire by four wickets|
Essex captain Simon Harmer came in to play a cameo captain's innings at the end to lead the Eagles to their first T20 title with a stunning final-ball victory over holders Worcestershire.
Chasing a Worcestershire total of 145-9, Essex looked on the ropes at 82-5.
But Ravi Bopara smashed an unbeaten 36 to keep them in touch, before Harmer came in to hammer 18 off just seven balls to see his side over the line on 148-6.
Worcestershire had faced the same situation of two needed to win off the last ball in their semi-final win over Notts, although one would have been enough in both games because their opponents had lost fewer wickets.
But Wayne Parnell could not repeat his earlier dot ball, as Harmer carved him to the square cover boundary to end Worcestershire's hopes of becoming the first team to successfully defend the T20 trophy.
The South African spinner, 30, who has been talked about as a likely candidate to qualify for England, had earlier starred with the ball.
He took 4-19 to set up his side's comfortable semi-final win over first-time Finals Day contestants Derbyshire, before following that with an even more economical 3-16 in the final.
It means one side will end up with two of this season's three domestic trophies this week, when new T20 kings Essex meet One-Day Cup winners Somerset at Taunton.
The County Championship's top two meet in a match that will decide the Division One title, starting from Monday.
Essex edge Edgbaston thriller
Having won the toss and put Essex in, the first-time finalists took just three balls to strike before Dan Lawrence bowled Hamish Rutherford.
It was to be 56 runs - and eight overs - later before they struck again when Harmer found himself on a hat-trick for the second time in the day.
On 32, Rapids captain Moeen Ali gave him a difficult low return catch, then Ben Cox - man of the match in last year's final - was lbw sweeping to the next delivery, with Wayne Parnell having to survive a huge shout to the hat-trick ball.
Riki Wessels battled on to the 16th over to make 31 off 34 balls, supported by 19 apiece from Parnell and Daryl Mitchell and a few late blows from Brett D'Oliveira, but it did not look enough.
It did not always seem that way, especially when semi-final half-centurion Cameron Delport holed out to long-off from the second ball of Parnell's first over.
Adam Wheater then reverse swept Mitchell onto his stumps, before Parnell returned to remove opener Tom Westley for 36 and Moeen struck twice to get rid of Ryan ten Doeschate and danger man Dan Lawrence.
But the tide started to turn again when quarter-final match-winner Bopara put the previously economical Moeen into the crowd off his last ball.
And, although Pat Brown ended Bopara's 47-run stand with Simon Walter, the nerveless Harmer came in to have the final word.
'I really, really wanted that' - reaction
Essex captain Simon Harmer told BBC Radio 5 Live Sports Extra:
"We said at the beginning of the competition it's always been about the County Championship and we're just happy to be in the T20, but I really, really wanted that.
"It was one of those days were everything came off, my bowling and my batting. It's a special night."
Essex all-rounder Ravi Bopara told BBC Radio 5 Live Sports Extra:
"Unbelievable, it's the one trophy we didn't have in the cabinet. I've won everything else with Essex and this was the one I was desperate for."
Worcestershire skipper Moeen Ali told BBC Sport:
"I'm disappointed with the result, but not with the performance. We have won a few tight games like that in the last few years and we came up short this time but it wasn't for a lack of effort.
"It was a great game of T20 cricket and full credit to Essex. Ravi Bopara was fantastic. He showed his experience and he basically won the game for them, along with Simon Harmer.
"We have a good record at this ground and, going forward, we have a formula that works for us in this. We now hope to be back here next year."