The show achieved an average audience of 6.5 million viewers, and peaked with 7.7 million throughout its initial airing.
Media executives suggested that the channel could expect to generate tens of millions of... However, they are also down on the figures enjoyed by the BBC for the first episode of the last series, which generated a peak audience of 11.2m and an average audience of 10.4m.
However, the figure which includes the Channel 4 "plus one" audience, still represents a drop of nearly four million compared to the opening episode from the previous series on BBC1.
Great British Bake Off starts tonight and we're getting all our eggs, flour and cookie cutting implements ready and in a row.
The episode was the first to be shown on Channel 4 since it paid £75m to take the show away from the BBC, which aired the first seven series.
But the show still won the channel its biggest overnight audience since the Paralympics Opening Ceremony in 2012.
Eyebrows were raised when the £75 million figure Channel 4, which is a commercially funded public broadcaster, paid for it became public.
Offbeat comedians Sandi Toksvig and Noel Fielding have replaced Giedroyc and Perkins as hosts, while the chef and writer Prue Leith has taken over for Berry as judge.
But if it wasn't for the adverts, Channel 4 wouldn't have been able to bag the Bake Off on their channel in the first place.
The turnover sprung from a decision by the show's producers, Love Productions, to move the popular series from the BBC, to a commercial rival that could pay a higher fee.
Advertising space is understood to have sold for between £150,000-£200,000 for a 30 second slot before, during and after the show - around £50,000 more than Channel 4 normally charges at that time.