Harry Redknapp's side were reduced to 10 men for the final 30 minutes after Gary O'Neil's red card, but Zamora punished a mistake by Richard Keogh to steal victory against the run of play and ensure the west Londoners will make a quick and lucrative return to the English top-flight after last season's relegation.
It was a real smash and grab raid by QPR, who struggled to find any rhythm even before O'Neil's dismissal and had only one shot on target in the entire match, but although Derby dominated they had only themselves to blame for failing to make the most of their chances.
QPR's triumph made them the first team to win promotion after finishing fourth in the second tier for 16 years.
But the historical significance of the victory will pale in comparison to the relief felt by QPR's Malaysian owner Tony Fernandes, who has funded a ?70 million wage bill reportedly higher than Spanish champions Atletico Madrid, while also coping with annual losses of around ?65 million.
In that context, promotion to the promised land of the Premier League, where QPR will now land a minimum windfall of ?80 million, was essential and Redknapp's men have delivered thanks to Zamora.
"We were trying to take the game to penalties and were hanging on for our lives," Redknapp said.
"I would be a liar if I said I thought we would score, but we worked hard and it was a fantastic goal
I couldn't be more pleased for the people at this club."
For Derby manager Steve McClaren, Wembley once again proved the most painful of venues.
"I've lost some games in my career but that is the cruellest," McClaren said
"We didn't deserve that
You could only see one winner."
It was McClaren's first time in the Wembley dug-out since November 2007 when his underwhelming spell as England manager came to a farcical end with the coach lampooned as the 'Wally with the brolly' after he huddled under an umbrella during a 3-2 defeat against Croatia that shattered his country's hopes of qualifying for Euro 2008.
If McClaren was a superstitious type he might have suspected the fates were aligning against him as torrential rain lashed down just before kick-off and he had a familiar sinking feeling by full-time.
In a scrappy first half, McClaren's men appealed in vain for a penalty when Will Hughes raced onto Jamie Ward's pass, cleverly turned back in the other direction and took a tumble after Richard Dunne's awkward challenge.
Robert Green came to QPR's rescue in the 40th minute when he plunged low to his left to turn away an inswinging free-kick from Ward that almost crept in at the far post.
- Desperate lunge -
The momentum swung towards Derby when O'Neil was sent off in the 60th minute.
Hughes seized on a loose pass and picked out Johnny Russell, who flicked the ball through Dunne's legs and appeared poised to bear down on goal until O'Neil's desperate lunge sent him crashing to the turf and brought a red card from referee Lee Mason.
McClaren's side tried to press home their numerical advantage and substitute Craig Bryson drew a smart save from Green before Chris Martin's near-post strike was repelled by the former England goalkeeper.
Green was keeping Derby at bay almost single-handed and he made another good stop to claw away Simon Dawkins' shot from point-blank range.
Derby were the division's top scorers with 84 goals, but they just couldn't find a way past a QPR defence superbly marshalled by Dunne.
And with extra-time looming there was an astonishing sting in the tale.
QPR winger Junior Hoilett showed great determination to win the ball wide on the right, but his cross should have been cleared by Keogh.
Instead the Derby defender diverted his clearance straight to Zamora, who could hardly believe his luck as he dispatched a fine first-time finish past Lee Grant to send QPR back to the big time.
Source : AFP
Source: AFP