Millar was only recently cleared to compete at the Olympics after a lifetime ban for doping from the BOA was overturned.
He will feature in the line-up for the 250km course - which starts and finishes at The Mall on the opening day of London 2012, July 28 - alongside Wiggins, who is currently second in the General Classification at this year’s Tour de France and considered one of the favourites for overall victory.
They join Cavendish, Chris Froome and Ian Stannard in the provisional team, with Ben Swift, Steve Cummings and Jeremy Hunt left out.
Cavendish, the 2011 road race world champion, will be a favourite for gold if the race culminates in a sprint.
In Copenhagen he was part of an eight-strong team, but the smaller Olympic field means he will have just four riders to support him in London.
Stannard is the national road race champion, while Froome was runner-up at last year’s Vuelta a Espana.
Both put in impressive shifts in Cavendish's cause in Denmark last September.
Froome and Wiggins have also been selected for the 44km time trial, which starts and finishes at Hampton Court Palace on August 1.
British Cycling performance director and Team GB cycling team leader Dave Brailsford said: “The final selection for the men’s road race was a tough choice as we had a really strong squad of riders to pick from. We have selected the five riders who we believe are on the best form and will give us the fastest team for the race.
"All the riders selected have a gruelling few weeks coming up, with Ian [Stannard] due to ride in the Tour of Poland and the rest of the lads riding in the Tour de France, so we’ll be keeping an eye on injury and form but for now, I am confident that we have picked the best team for the race.”
However, maintaining race discipline and setting Cavendish up for a sprint finish on The Mall will not be easy.
He won last year's test event but that was over a shortened course, with only two loops rather than nine of Box Hill in Surrey, the most gruelling element of the course.
"The course looks challenging – the laps around Box Hill are going to be hard and will make the race interesting. We’ll be there with Cav to support him and it should be a really good course for us," said Froome.
"It’s huge to compete at home – the British support out here at the Tour de France has been amazing and I can only imagine it'll be even bigger at home. If it’s anything like the test event, it will be a big spectacle for the public to come and watch.”
Wiggins, whose Olympic focus is the time trial alongside Millar, insists he is happy to work as a domestique to Cavendish, even though he hopes to roll off the line in London as the new Tour de France champion.
“I’m happy to be a part of it, we’ve got a good chance to win the road race with Cav and it’s a London Olympics which makes it very special," he said.
"I’ve also got a chance to go for my fourth gold medal in the time trial.”