Under the agreement, which follows a failed negotiation with the BBC, ITV will show a daily highlights programme on its digital terrestrial channel ITV4 at 10:00pm during each match.
The deal also covers the Twenty20 and one-day international series between Australia and England in January and February.
ITV showed this year's Indian Premier League exclusively on UK television on ITV4.
"There is huge demand to see England defend the Ashes and I'm delighted that we have secured highlights, free-to-air for UK viewers," said ITV's controller of sport Niall Sloane.
The first match of the Ashes series begins in Brisbane on November 25.
