An average of 5.3m viewers tuned in to the match to watch England beat South Africa 25-6, with viewer numbers peaking at 6.1m. It attracted 53.2% of the available audience, rising to 57% in the closing stages.
An ITV spokesperson said: "Once again, the figures are extremely encouraging and show the appetite that viewers have for England's quest to win the World Cup for the first time.
"The game was the biggest so far of the competition, and augurs well for the knockout stages of the event."
With England standing a real chance of winning the World Cup this year, combined with the emergence of a Beckham-like figure in the form of fly-half Jonny Wilkinson, rugby is attracting widespread interest from audiences, the media and sponsors.
Foreign currency company TravelEx has signed a £3.5m deal to sponsor all of the matches shown on ITV1 during the Rugby World Cup, which kicked off on October 10 and finishes on November 22. England's defeat of the Springboks will give them an easier route to the final, avoiding matches with the New Zealand All Blacks and the Australian Wallabies.
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