Mr Johnson has been linked with several constituencies amid growing rumours he will return to Westminster.
His chances of being elected at next May's poll will have been boosted by the news that Sir John Randall is not seeking re-election in Uxbridge & South Ruislip.
Sir John, who has a majority of 11,216, told his constituency party it has been a "privilege and honour" to represent the Middlesex seat for the past 17 years.
Mr Johnson - whose term runs to 2016 but would be allowed to continue at City Hall at the same time as serving as an MP - has been linked with a series of safe Conservative seats. But the former MP for Henley in Oxfordshire has continually ducked demands to declare his intent to stand in the 2015 general election or in a by-election before then, despite Prime Minister David Cameron backing his return to Parliament.
The Tory leader has described his fellow Old Etonian, among the favourites to succeed him as Conservative leader, as a star striker missing from his team.
Sir John stepped down as deputy chief whip in October after a long career in the Tory whips office and Mr Cameron said he "could not have wished for a more loyal, discreet, patient, trustworthy colleague" and described him as a "rock" for the party.
However, sources close to Mr Johnson described suggestions he could seek to fight the constituency next year as "nothing more than speculation and rumour around another vacant seat" and said he was "getting on with the job of mayor".
The mayor's official spokesman said: "The mayor is focused on one thing: delivering on his second- term commitments for London - the continued creation of jobs and growth, the provision of new housing to meet growing demand, and the further reduction of crime in the city."