At noon AEST, the benchmark S&P/ASX200 index was up 45.2 points, or 0.59 per cent, to 7,760.7, while the broader All Ordinaries was up 50.1 points, or 0.63 per cent, to 8,013.2.
Overnight the US Labor Department reported that US consumer prices rose 3.3 per cent in the year to the end of May, down from 3.4 per cent the month before.
Hours later, the Federal Reserve left interest rates unchanged, as was widely expected, while forecasting it would cut interest rates once this year - down from the three cuts officials had predicted in March.
Rob Hogg, chief investment officer at SG Hiscock & Company, said while the Fed's announcement was "mildly bearish," the "extremely encouraging" CPI report was having more of an impact on markets.
"From a monetary policy standpoint, the easing of underlying inflation pressures is extremely positive as it is an easing in inflation that will enable the US Fed to cut rates if economic growth continues to soften," Mr Hogg wrote.
Closer to home, the Australian Bureau of Statistics reported shortly before noon that the unemployment rate fell by a tenth of a percentage point to 4.0 per cent in May.
Krishna Bhimavarapu, APAC economist at State Street Global Advisors, said employment growth had been broadly in line with expectations in May and the figures would probably not swing the Reserve Bank's general assessment of the economy.
Nine of the ASX's 11 sectors were in the green at midday, all except energy and materials.
Tech was the biggest gainer, up 2.1 per cent as Wisetech Global rose similarly and Xero added 2.5 per cent.
All of the Big Four banks were higher, with CBA up 0.8 per cent, NAB climbing 0.7 per cent, Westpac adding 0.3 per cent and ANZ gaining 0.2 per cent.
Shares in the ASX itself were down 8.7 per cent to a six-month low of $57.73 as the bourse said it expected to spend between $160 million to $180 million a year on technology through 2026/27.
"Continuing to invest in our business is critical to our strategy," said ASX chief executive Helen Lofthouse.
In the heavyweight mining sector, BHP was down 0.7 per cent and Rio Tinto had dipped 0.3 per cent, while Fortescue was flat at $23.29.
The Australian dollar was buying 66.51 US cents, from 66.13 US cents at Wednesday's ASX close.