The Bee Gees singer died of kidney failure in May, aged 62, following a battle with cancer and pneumonia.
The Heritage Foundation and Thame Town Council have installed the plaque at Gibb's home The Prebendal, in Priestend, Thame.
Gibb, who was appointed CBE in 2004, was president of the Heritage Foundation from 2008 to 2011.
Fans from all over the world, including Canada, America and New Zealand, had travelled to be at the unveiling, along with Sir Tim Rice and DJ Mike Read, and other friends of the singer.
David Graham, chairman of the Heritage Foundation, said: "It's a chance for them to come over to say a final goodbye to Robin and it's a very nice way of remembering Robin.
"There's a great deal of feeling there and a great deal of affection."
Vicki Michelle, who took over as president from Gibb, unveiled the plaque on the gatehouse wall at the entrance to the property at 14:20 BST.
The ceremony was followed by a charity garden party for 400 people in the grounds of The Prebendal, with all money raised going to the Bomber Command Memorial Maintenance Appeal Fund.
In 2008, Gibb was at the forefront of the campaign for a permanent memorial in London to the men of Bomber Command.
But he never lived to see it being unveiled in Green Park, in June.
"If the measure of man's life is what he achieved, Robin achieved so much it's immeasurable," continued Mr Graham.
"I hoped we would never have had to put up a plaque for Robin in my lifetime. He put up such a fight."
A blue plaque has been unveiled at the Oxfordshire home of the late musician Robin Gibb.