Trees for Cities' top 20 include entries in Barnet, Camden and Westminster. All are the latest in the Great Trees of London, established by the charity over 20 years ago.
Londoners nominated the trees, which included nine London planes, in a competition judged by an expert panel of horticulturists and worthies including TV celebrities.
Trees were nominated on their historic ties, location and physical characteristics such as size, age or shape
The ceremony included a plaque unveiling this week at a plane at Regent College.
The Great Trees of London list was launched after the great storm of 1987.
Public figures like Jon Snow, Chris Collins and Shazia Mirza helped nominate trees.
The project is supported by Barratt Homes, The Forestry Commission and Magic 105.4.
Presenter Neil Fox nominated a London plane that stands at the junction of Embankment and Horse Guards Avenue.
Forestry Commission chairman Lord Clark of Windermere said: "There are more ancient trees in Great Britain than anywhere else in Europe.
"Many are older than our historic buildings and they continue to live and grow. We must work together to ensure the ancient trees of tomorrow are spared destruction.
Graham Simmonds, chief executive of Trees for Cities, said: "Trees breathe freshness into bleak urban areas. These 20 help define London's cityscape. "
Which are the 20 Great Trees?
Japanese Maple, Hendon Park Barnet
Common Ash, Old St Pancras Churchyard Camden
London Plane, Brunswick Square Gardens Camden
London Plane, Regents Park Camden
London Plane, Cheapside, City of London City of London
Cedar of Lebanon, Forty Hall, Enfield Enfield
London Plane, Ravenscourt Park Hammersmith & Fulham
Cork Oak, Osterley Park Hounslow
Common Fig, Amwell Street, Islington Islington
English Oak, Brockwell Park Lambeth
London Plane, Brixton Oval Lambeth
Common Fig, Stratford High Street Newham
Field Maple, Valentine Park, Ilford Redbridge
English Oak, Richmond Park Richmond
Sweet Chestnut, Carshalton Park, Sutton Sutton
Huntingdon Elm, Marylebone High Street Westminster
London Plane, Embankment Westminster
London Plane, Berkeley Square Westminster
London Plane, Gower Street, Westminster Westminster
London Plane, Westminster Abbey Westminster
What makes a great tree?
It should be
- historically significant - related to past events and/or people, or with a story to tell
- situated in a landmark location - somewhere special
- be of notable physical character - very large, or old, or of an unusual shape