Boris Johnson today phoned local Conservatives in Uxbridge and South Ruislip to tell them; "I've whacked my application in".
The Mayor called Hillingdon council leader Raymond Puddifoot to confirm he was throwing his hat into the ring for the safe Tory seat in west London.
Mr Puddifoot said Boris would be a "huge asset" to the Conservatives - but warned he would need to perform as a constituency MP if his application is successful.
"Boris rang me just before one o'clock to tell me he was applying," Mr Puddifoot told the Standard. "His very words were; 'I've whacked my application in'."
But he warned: "He has got to make the selection, and there will probably be three candidates.
"Boris would be a huge asset to the national Conservative scene - I think he has that reputation. The issue he will have is how will he perform as a constituency MP, but he has done it before."
Mr Johnson will now be the hot favourite to be selected to replace the retiring Sir John Randall, who has a majority of 11,216.
"I am sure there will be plenty of excellent candidates and I look forward to making my case to the association," he said today.
If selected as an MP in 2015, Mr Johnson says he plans to stay on as Mayor until his City Hall term ends the following year.
A poll commissioned by the former Conservative Party chairman Lord Ashcroft found that voters in the constituency would be more likely to back the Tories if Mr Johnson was selected. The Conservatives' share of the vote swelled from 42 per cent to 52 per cent if the Mayor was chosen to fight the seat, the poll found.
If selected, Mr Johnson will complete a dramatic return to Westminster after he left Parliament to become London Mayor. He was previously MP for Henley from 2001 to 2008.
