MORE: WARATAHS VS BRUMBIES PHOTOS
It is the Waratahs' third final – they have never won a title - and their first-ever home decider.
The Crusaders, who beat the Waratahs in the 2008 final to claim their seventh Super Rugby title, booked their place with an ominous 38-6 demolition of the Sharks in Christchurch earlier on Saturday night.
Michael Cheika's men led from the third minute after an early runaway try to Alofa Alofa but the plucky Brumbies drew level late in the first half before the Waratahs edged 11-8 ahead at the break.
The Waratahs' second try also came against the run of play when Kurtley Beale made a one-on-one strip on Jesse Mogg and sprinted 20m to score early in the second half.
But if wasn't going to be easy for the Tahs or the parochial 38,800 crowd as the Brumbies spent almost 20 minutes camped in the hosts' half.
NSW finally made it into enemy territory and Bernard Foley slotted his third penalty of the night before scoring the match-winning try four minutes from full-time after some brilliant work from man mountain Will Skelton.
Skelton beat several Brumbies defenders before throwing a beautiful ball for Foley, but the giant lock could be in strife for a high shot on Nic White earlier in the second half.
Reserve back Taqele Naiyaravoro also faces a nervous wait after he was yellow carded for a shoulder charge on pat McCabe in the dying moments.
It was a gutsy effort from last year's finalists who lost star winger Henry Speight to a hamstring injury in the 53rd minute, but the Brumbies' failure to turn pressure into points ultimately cost them.
The Waratahs made a dream start when Alofa swooped on a loose pass from Nic White and sprinted 60m to score the opening try of the contest.
Brumbies full-back Jesse Mogg chased valiantly but Alofa has just enough pace to dive over for an early 5-0 lead.
The hosts stayed on top and increased their lead via a Foley penalty goal in the 22nd minute.
Momentum then swung the visitors' way.
They turned down four kickable penalties before their dominance was finally rewarded with points when Henry Speight cruised over on the short side.
The Tahs continued to get on the wrong side of referee Jaco Peyper and Christian Lealiifano slotted a gift three points in the 39th minute after the Brumbies were awarded a sixth straight penalty.
Foley answered after the siren to give the hosts a three-point cushion at the break.
Israel Folau was hardly sighted in the first half and he put his team under immediate pressure with a forced offload.
The Brumbies earned another penalty but Lealiifano badly hooked his close-range attempt to continue to trail 11-8.
They made the most of their let-off when Beale struck before finishing off the gutsy Brumbies in the final 10 minutes.
Waratahs: 26
Tries: Alofa, Beale, Foley,
Cons: Foley 1/3,
Pens: Foley 3/3,
Brumbies: 8
Tries: Speight,
Cons: Lealiifano 0/1,
Pens: Lealiifano 1/2,