Mr Paddick, who also ran in 2008, beat outgoing London Assembly Member Mike Tuffrey, former Haringey Councillor Brian Haley and defeated MP and reality TV star Lembit Opik in a ballot of party members.
Mr Paddick polled 1,575 votes, just 91 more than Tuffrey.
On the first round the order of candidates was Paddick, Tuffrey, Haley and Opik, in the second round the votes split 51.5 per cent for Paddick, 48.5 per cent for Tuffrey.
The next Greater London Authority elections, at which voters will elect the Mayor and London Assembly, take place in May 2012.
The campaign will see Paddick reunited with fellow 2008 Mayoral runners Boris Johnson (Conservative) and Ken Livingstone (Labour).
Of the four parties represented at City Hall, only the Greens are offering a new candidate in 2012. In March the party selected three-term Assembly Member Jenny Jones.
During the selection process Mr Paddick, whose 2008 campaign saw the party’s share of the vote fall by over 5% from the previous election, said he had “learnt from my mistakes” and was now better equipped to take on Livingstone and Johnson.
Members will be hoping he’s able to translate those learnt lessons into votes in the Assembly elections amid speculation the party could lose at least one of its three seats at City Hall.
Speaking after the result was declared, Mr Paddick said: “I am excited to be joining an excellent team of Assembly Candidates for the 2012 Greater London Authority elections.
“My number one priority is to improve the image and standing of the party in the eyes of the public, with a view to securing the maximum number of votes for the Liberal Democrats in the 2012 elections and beyond.”
Commenting on the result, Jenny Jones said: “The Lib Dems have made the same mistake twice in selecting Brian Paddick as their mayoral candidate.
“Although with a higher profile than others, his background is not embedded in Lib Dem culture and he might find it hard to motivate the activists who, by and large voted for Mike Tuffrey. Getting party members to turn out on wet wintry Wednesday nights, to leaflet or canvass, is very hard and needs real enthusiasm and support from the candidate. Will Paddick rouse that loyalty in the Lib Dems?”
Confirmed Mayoral Candidates
Boris Johnson – Conservative
Jenny Jones – Green Party
Ken Livingstone – Labour
Brian Paddick – Liberal Democrats
