South West Surrey's MP Jeremy Hunt and local Councillors joined the Transport Secretary Philip Hammond, who performed the official opening.
Jeremy said: "Not a few old hands thought they would never see the day when Hindhead finally got a tunnel. But it has finally happened - on time and to budget. I remember the first debate I ever secured in parliament was to campaign for the tunnel so it is a dream come true for me and many others who have campaigned for far longer than I have. Virginia Bottomley in particular deserves a lot of credit for never giving up. Finally the people of Hindhead have got their village back."
Construction began on the tunnel in 2008 and was completed earlier this year. By replacing the only piece of single-carriageway between London and Portsmouth with a dual carriageway it will cut journey times from London to the coast and reduce congestion through Hindhead.