The S&P/ASX200 hit a record intraday peak of 8,848.8 points before settling at its highest-ever close of 8,843.7, up 73.3 points, or 0.84 per cent for the day.
The broader All Ordinaries rose 82.3 points, or 0.91 per cent, to its own record-high close of 9,111.1.
The relentless run-up, despite global headwinds of US tariffs and lumbering economic growth, continued to surprise AMP chief economist Shane Oliver.
"It seems like our market is ignoring that, given optimism about future rate cuts and so-far some okay or good profit results," Dr Oliver told AAP.
"But that said, we are trading on relatively rich valuations for the market and that does leave us a little bit vulnerable if anything goes wrong."
Materials, energy and consumer discretionary stocks led 10 of 11 local sectors higher, while interest rate-sensitive segments such as financials, real estate and IT stocks surged on expectations of cheaper incoming borrowing costs in Australia and the United States.
Wednesday's milestone session was spearheaded by recent strength in the big miners, IG Markets analyst Tony Sycamore said.
"They have regained favour following a shakeout last week after Rio Tinto's lacklustre earnings, supported by strong results today from REA, News Corp and Pinnacle Investments," he told AAP.
Pinnacle was the top-200's best performer rallying 9.5 per cent to $25.21 posting a nearly 50 per cent lift in full-year net profit to $134.4 million.
REA Group shares jumped 6.9 per cent after posting a double-digit boost to earnings and net profit and News Corp, which holds a controlling stake in REA, gained more than five per cent after its results impressed investors.
Iron ore prices are at their highest level since May and continued strength in gold helped local miners take several places on the daily leaderboard, with Stanmore, Capricorn Metals and West African Resources all rallying more than five per cent.
Fortescue was the best of the large cap miners, pushing 1.3 per cent higher to $18.58, followed by Rio Tinto (+1.0 per cent) and BHP (+0.3 per cent).
Gold is trading at $US3,432 ($A5,286) an ounce, roughly two per cent short of its record peak above $US3,500 an ounce, supported by expectations of lower interest rates, which boosts its attractiveness relative to yield-bearing assets like bonds.
Investors shrugged off concerns of lofty valuations in Australia's heavyweight banking sector, as the Commonwealth Bank gained one per cent to $179.08 per share, its recent 10 per cent correction from its $192 record proving short-lived.
The financial sector pushed 0.8 per cent higher over the session.
Energy stocks outperformed the broader market, rising 1.3 per cent, tracking with similar gains in Woodside and Santos after oil prices staged a modest rebound.
Coal producers performed even better, with Yancoal and New Hope Corporation each gaining more than 2.5 per cent, after data pointed to an uptick in coal imports to Asia in July.
While the market celebrated new highs, its operator the Australian Securities Exchange was forced to blush after tagging TPG Telecom in an unrelated takeover deal by TPG Capital, wiping as much as $437 million from the telco's market cap.
The Australian dollar is higher against most major currencies, buying 64.90 US cents, up from 64.60 US cents on Tuesday at 5pm.
ON THE ASX:
* The benchmark S&P/ASX200 index on Wednesday gained 73.3 points, or 0.84 per cent, to 8,843.7
* The broader All Ordinaries rose 82.3 points, or 0.91 per cent, to 9,111.1
CURRENCY SNAPSHOT:
One Australian dollar buys:
* 64.90 US cents, from 64.60 US cents on Tuesday.
* 95.76 Japanese yen, from 95.17 Japanese yen
* 56.05 euro cents, from 55.93 euro cents
* 48.79 British pence, from 48.65 British pence
* 109.66 NZ cents, from 109.68 NZ cents
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