The 39-year-old former U.S. Open champion found his putting touch to pocket six birdies on the front nine and two more over his last three holes in a flawless third round that left him 11-under for the tournament.
World number five Spieth came through a wobbly start at Royal Sydney to shoot a 68 for a share of second place with Aaron Baddeley (67) and New Zealander Ryan Fox (71).
Adam Scott would have had a share of fifth with Rod Pampling (70) a further shot back had he not missed a birdie putt from two feet at the last, but the former world number one will still fancy his chances of making up four shots on Sunday.
Scott, now ranked seventh in the world, carded a 71 for a share of sixth with fellow Australians Lucas Herbert, Jake Higginbottom, James Nitties and Jason Scrivener.
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Adelaide-born Ogilvy, winner of the Stonehaven Cup in 2010, started the day six shots off the pace but soared into the lead with the best round of the week in the best weather conditions of a blustery day.
If the left-to-right putt from 12 foot for a fourth birdie in a row at the ninth hole showed his confidence on the greens, the approach shot which left him with a two-footer for his eighth birdie at the 18th was the perfect way to finish.
"What a difference a few putts going in makes," Ogilvy said.
"It makes everything feel a little easier, my golf swing felt better as I went along. Just got my head down and finished well.
"I'm just glad I'm back in the mix. I've just got to try and go out and do it again tomorrow."
Spieth was one-over after five holes but birdies at the sixth and seventh then three more from the 12th, the first two set up by stunning approach shots and the third completed with a sublime curling putt, showed he had found his rhythm.
The 23-year-old lipped out with a par putt on 15 but a sixth birdie after a fine recovery at the 16th left him well placed for a second Australian Open title after his 2014 triumph.
"I felt more comfortable when I was putting today," said the twice major champion.
"I don't know if three-under gets the job done tomorrow. Someone may shoot five or six-under, so I may need to go lower tomorrow, but certainly in contention, in a good position."
Fellow former U.S. Masters champion Scott was again left cursing his profligacy with the putter after spurning an opportunity for a fifth birdie of the day after a brilliant approach shot to the final green.
"It would have been nice to get that putt on the last and get that one closer, it would have felt nice," the 36-year-old, winner of his home open in 2009, said.
"But a hot start tomorrow is what I need. A quick front nine and I'll be right in it."
(Editing by Peter Rutherford)
