The Edinburgh-born cyclist carried the Union Flag at the closing ceremony in Beijing four years ago.
The four-time gold medalist, who is Scotland’s most successful Olympian, won the biggest number of votes among the 542 members of the British team.
He said: “I’m absolutely delighted and honoured to have been voted as the flagbearer for Team GB. To lead out your team at a home Olympics is truly a once-in-a-lifetime opportunity and one that I can’t wait to experience in just a few days’ time.”
Team GB will be the last of the 204 competing nations to enter the Olympic Stadium on Friday.
First Minister Alex Salmond, who will be travelling to London as part of a trade delegation ahead of the Games, passed his congratulations to the 36-year-old cyclist.
“He is Scotland’s most successful Olympian and it is fitting that he will carry the flag at the opening ceremony,” Mr Salmond said.
“This is a great honour for Chris and I know the whole country will be wishing him well as he aims to add to his already fantastic medal tally at these Games.”
Hoy will defend two of the three gold medals he won in Beijing in the team sprint and keirin events.
Victory in both events would see him surpass Sir Steve Redgrave’s British record of five gold medals.