Eight hours after polling stations closed, the results were announced shortly after 6am today.
Mr Vaizey's victory means that the Wantage constituency - which has been in Labour hands since Robert Jackson's sudden defection in January - is returned to the Tory fold.
Supporters cracked open bottles of Champagne to celebrate the victory.
Mr Vaizey, tipped as a future leader of the Conservative Party, said: "This is one of the proudest moments of my life. I love the constituency and intend to serve it as well as I possibly can over the next four years -- I am proud as punch."
Liberal Democrat candidate Andy Crawford said: "I am pleased with second place -- we have more votes this time than we did last time and we have moved from third to second and put clear blue water between ourselves and the Labour party, we are now the clear challengers to the Conservatives."
Deflated Labour challenger Mark McDonald added: "I congratulate Ed in his victory but he must remember that this constituency for the first time was Labour's -- we will continue to ensure that the Labour message is put forward in this constituency."
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