Iniesta struck with four minutes remaining to settle a tetchy encounter which saw English referee Howard Webb brandish a record 12 yellow cards, plus a red for Everton's John Heitinga on a night when Holland shamed the 'Total Football' for which they have been synonymous since the first of what is now three final defeats in 1974.
- Holland 0-1 Spain: As it happened
Webb deserves a huge amount of credit for not setting a new record for red cards, let alone yellow, the first of which he showed to Robin van Persie in the 14th minute.
Pretty soon combative midfield duo Mark van Bommel and Nigel de Jong joined him for challenges that could easily have ended their evening.
The feeling that if the match had been played on a park pitch rather than being a showpiece occasion watched by an estimated three billion, one, or both, would have been sent off was inescapable.
Van Bommel's challenge on Joan Capdevila was bad enough. De Jong's karate kick on Xabi Alonso was awful.
That Wesley Sneijder was not even cautioned for a similarly woeful attempt at stopping Pedro could only be put down to either Webb being unsighted or the Dutch playmaker diverting attention by claiming to be injured himself.
Spain were not complete innocents in all of this. But it was the European Champions who were feeling most aggrieved, which only intensified when Webb did not see a niggly second-half challenge from Van Bommel that sparked a reaction from Barcelona playmaker Iniesta.
Vicente del Bosque was particularly annoyed, jabbing his finger at either Webb or Van Bommel, who were both in roughly the same area of the pitch.
It made for such unsightly viewing and a final which did not even come close to matching its billing.
In fairness any game that is preceded by an appearance from Nelson Mandela is going to struggle to live up to expectations.
However, as the rather tasteless celebrations of Uruguay's Luis Suarez showed after his "real Hand of God" that denied Ghana a place in the semi-final, the ends justify the means.
And that is exactly how Holland would have viewed it if Iker Casillas had not made a quite brilliant save to deny Arjen Robben after the former Chelsea star had been set free by Sneijder.
Robben must have thought he had done everything right.
Running at pace until he saw the whites of Casillas' eyes, he shaped to go one way, then placed his shot to the other corner.
Casillas was committed in the other direction but stuck out a leg and turned the effort wide.
It was by some distance the best opportunity of the regulation 90 minutes, although Sergio Ramos had a couple of decent openings himself, both headers, both from crosses from Xavi.
On the first occasion, Maarten Stekelenburg flung himself to his right and made the save at a point early enough in proceedings that a goal could have changed the contest completely.
By the time, unmarked, Ramos headed Xavi's corner over, Webb had become as much part of the occasion as the players.
It was the only Englishman to survive beyond the last 16 that Robben ran to when he threatened to sprint through again, only to be denied by Casillas.
But losing possession did not come before Carles Puyol had made a desperate grab for the Bayern Munich winger, who was convinced the Barcelona defender should have been sent off.
On as a substitute, with a point to prove after mustering the grand total of 93 minutes prior to tonight, Arsenal's Cesc Fabregas twice came close to breaking the deadlock in extra-time, when Xavi also had a penalty claim turned down.
But Spain were not to be denied. Fabregas slotted it through to Iniesta and after one touch to control it, his second was a crisp volley past Stekelenburg.
The loss of Fernando Torres to a hamstring injury in stoppage time may have further consequences for Liverpool.
But in Madrid and Barcelona that will not matter. In Amsterdam, only a shattered reputation remains now.