The Waratahs dreams of a first title in their third final were hanging by a thread when the Wallabies flyhalf calmly slotted his seventh penalty of the night from 44 metres to send the record crowd of 61,823 at the Olympic Stadium into raptures.
The Waratahs also had tries either side of half time from centre Adam Ashley-Cooper but they had to dig deep in the second half when the Crusaders erased an early deficit and took a slender lead.
It was a first win in 12 matches over a decade against the New Zealanders, who had won the first two finals between the teams in 2005 and 2008.
"The Crusaders really lifted their game in the second half and showed why they're the kings of the finals," said Waratahs coach Michael Cheika, who has transformed the underachieving state side in his two years at the helm.
"But we've been working really hard on our persistence all year and it paid off for us."
The Crusaders had tries from flanker Matt Todd and winger Nemani Nadolo - his 12th of the season - along with 20 points from the boot of flyhalf Colin Slade but their wait for an eighth title will now go into a seventh season.
The Waratahs, as they have often this season, started at a canter and were 8-0 up inside five minutes after Foley kicked his first penalty and Ashley-Cooper finished off a breathless move by barging through three tacklers to touch down.
The Crusaders appeared shellshocked by the Waratahs' opening salvo - making uncharacteristic handling errors and looking fragile at the set piece - and two more Foley penalties extended the lead to 14-0 after 15 minutes.
The New Zealanders had too much quality to simply lie down, though, and from a counter-attack from inside their own 22 on 18 minutes, number eight Kieran Read offloaded to flanker Todd, who brushed off Ashley-Cooper's tackle to score in the corner.
Dan Carter added the extras in one of his last contributions before he departed the contest on the half-hour mark with a corked thigh, leaving Slade to trade a couple of penalties apiece with Foley before the break.
Waratahs players celebrate victory at the end of the Super Rugby Grand Final match between the Waratahs and the …
Three minutes after halftime and the scores were all square at 20-20 after another sweeping Crusaders counter-attack resulted in Nadolo touching down in the corner.
It was a controversial decision confirmed by referee Craig Joubert only after review of the TV pictures, which suggested the Fijian's foot might have gone into touch.
Slade converted and added a penalty after the Waratahs scrum collapsed under pressure in the 48th minute to put the Crusaders ahead for the first time at 23-20.
Foley missed a chance to level the scores a couple of minutes later but made no mistake with his next attempt only for Slade to slot another penalty to maintain the three-point cushion.
The Crusaders were now dominating the breakdown but the Waratahs stuck to their task and managed to get enough quick ball to launch another assault with Ashley-Cooper again crashing through tacklers to give the home side the lead at 30-26.
Slade kicked two more penalties, though, to give the Crusaders a two-point lead but ultimately it only set the stage for Foley, who got his chance when Richie McCaw infringed at the breakdown.
"We're absolutely gutted," said Crusaders skipper Read.
"We definitely started slowly and I was proud of the way we fought back. In the end it came down to one kick. That's footie I guess."
The crowd was a record for a Super Rugby match, beating the 55,000 that watched the Bulls beat the Waikato Chiefs in the 2009 final in Pretoria.
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- Adam Ashley-Cooper
- Colin Slade