Australia’s five-wicket victory completed the T20I series, with England triumphing 2-1, but the visitors will be encouraged by their final display ahead of the three 50-over matches this week.
England, without top order blaster Jos Buttler, were restricted to 6-145 from their 20 overs, with Adam Zampa taking 2-34 and Mitchell Starc producing an economical spell of 1-20 from his four overs.
Spinner Ashton Agar got the key wicket of Jonny Bairstow who top scored with 55 from 44 balls, while Joe Denly added some late runs with 29no from 19 balls.
In reply, Australia were always on track with their run rate but lost wickets regularly with Adil Rashid causing chaos with a super spell where he ended with 3-21 from four overs, although Bairstow inexplicably dropped a high chance from Finch.
Wavering at 4-87 in the 11th over, Marsh took charge with an unbeaten 39no from 36 deliveries to steady the ship and guide Australia to victory. He received good support from state teammate Agar (16no from 13).
“I loved tonight, loved finishing off the game for the boys and contributing to a great win,” Marsh said.
“It’s a hard spot to bat, finishing the game you find yourself in different situations.
“I was thinking about it tonight, just loving the experience of that again, getting out there and having that feeling of being under pressure.
“That’s why we play, that’s why we play hard. Just rapt to be able to contribute after a long layoff to a great win.”
The three-match One Day International series begins in Manchester on Friday.