The new ad, which was created by Chris and Siân Wilkins, debuted on ITV during an episode of Surprise Surprise on 26 July.
The spot shows Gio Compario performing a slowed-down version of GoCompare.com's theme song with the Prague Philharmonic Orchestra to a packed theatre.
According to a spokesman for GoCompare.com, the ad reached 8.7 million people on its debut and will be backed by a multi-channel campaign, which includes outdoor and digital advertising.
Campaign reported that GoCompare.com was bringing back Gio Compario in April. The opera singing mascot's irritating qualities were acknowledged in ads, created by Dare between 2012 and 2013, that showed celebrities and members of the public killing Compario before he could start singing.
When Fold7 took over GoCompare.com's ad account in 2013, Compario was dropped from the ads altogether. But GoCompare.com split with Fold7 earlier this year, the agency citing creative differences as the reason.
The new ad was created by Chris and Siân Wilkins, the team behind the original Gio Compario ads. The "#GioReturns" spot was directed by Graham Rose through the PI Film Network.
Carat handled the media planning and buying while Isobar worked on the outdoor advertising for GoCompare.com.
Nicholas Hall, GoCompare.com’s head of creative and broadcast, said: "Over the years our brand mascot has been hugely successful in informing the British public that Gocompare is the place to go for great deals on a wide range of products.
"The return of Gio, in a multi-media digital world, has allowed us to not only use just broadcast television but all of the other digital media opportunities available today.
"The campaign is easily the biggest we have ever done and has been designed to position GoCompare.com as the leading brand that we are."
Wynne Evans, who plays Gio Compario, said: "After a short break, it’s great to be back behind the moustache as Gio Compario. We’ve really gone all out to make sure that the new song has been produced to the highest standard.
"I’m incredibly proud of the music and I’m looking forward to the public hearing it."