Eoin Morgan’s men will now face New Zealand, whom they beat by 119 runs in the group stage, in the showpiece match at Lord’s on Sunday.
After Australia had opted to bat first, Chris Woakes, Jofra Archer and Adil Rashid reduced them to 14 for three on their way to a lacklustre 223 all out.
England would have been mindful that they were bowled out for 221 and beaten by the same attack last month, but Jason Roy missed that game with a torn hamstring and his brilliant 85 saw the hosts home by a more-than-comfortable margin.
Having smashed nine fours and five sixes, he would surely have gone on to a hundred had he not been given caught behind despite making no contact with the ball.
He instantly called for a review only to belatedly realise Jonny Bairstow had already used the last one up.
Roy lost his cool, on the pitch and on his reluctant walk-off, and needed soothing words from umpire Marais Erasmus to stop things getting worse.
A decisive stand of 79 between Joe Root (49no) and Eoin Morgan (45no) followed.
Both captains had hoped to win the toss and bat first, following the trend of the tournament, but it fell Aaron Finch’s way. However, he was pinned lbw by Archer’s opening delivery before David Warner fenced Woakes to slip for nine .
Woakes added a second scalp when he bowled Peter Handscomb for four via an inside edge.
There was further danger for the Aussies when Archer rattled Alex Carey with a bouncer, cutting open his chin and dislodging his helmet. Had his headguard hit the stumps it would have been 19 for four, but Carey had enough about him to trap it with his arm.
He and Steve Smith would go on to add a battling 103, restoring some stability.
Carey (46), however, was one of two wickets in Rashid’s fifth over, caught at deep midwicket, before Marcus Stoinis was bamboozled by a googly. Rashid later added a third when Pat Cummins poked to slip.
Smith’s determination took the total past 200, but there was no support. Glenn was deceived by Archer, Woakes did for Mitchell Starc and Jason Behrendorff was yorked by Mark Wood. Smith finally departed for 85, run out by the alert Jos Buttler.
For England, Roy and Bairstow quickly put on 50 without loss. Thirty of those came in boundaries, both men driving through cover and point and Roy adding a flicked six over fine leg when Starc strayed.
Australia turned to spin but Nathan Lyon’s first over was blasted for 13, Roy slapping his first ball down the ground for six before middling a reverse-sweep.
The first over of Starc’s second spell went for 15 as both openers drove him hard.
Finch gambled on Smith’s part-time leg-spin but Roy launched three successive sixes over long-on.
Bairstow was unable to kick on, lbw to Starc for 34, a record 27th tournament wicket for the left-armer. Unconvinced, Bairstow used England’s review, a fact that would come back to haunt his partner.
Given out to a steepler from Cummins, Roy instantly signalled for DRS with neither he nor Dharmasena aware the allocation had been taken. It took a reminder from Australia’s fielders to quash the process, leaving Roy to remonstrate long and loud before accepting his fate.