About 3,000 children were without places when offers were sent to parents in time for this week's deadline, compared with 8,400 in 2004.
The figures are a relief for supporters of the pan-London co-ordinated admissions project which was criticised last year after software problems left more children than expected without a school place.
Ian Birnbaum, chair of the project and director of children's services in Sutton, said the new system had almost eliminated parents holding places at more than one school.
He said: "This year has gone really smoothly. We have reduced the number of children without an offer by about 64 per cent since 2004 and that is entirely due to co-ordination."
The system was introduced last year to improve the allocation of places to the 77,000 pupils who move from primary to secondary school in 39 local authorities in and around the capital.
It covers state secondaries and academies, but not city technology colleges, in all 33 London boroughs as well as Essex, Surrey, Hertfordshire, Buckinghamshire, Kent and Thurrock. The project gives parents the chance to list up to six schools in order of preference on a single form. Their child is then allocated a place at the highest school on their list which accepts them.
Dr Birnbaum said last year's problems, caused by software trouble, left 4,800 children without an offer of a place. By contrast, the 3,000 left without a place this year suffered from a geographical mismatch between supply and demand.
Dr Birnbaum is confident that all children will be allocated a place, possibly by the end of the summer term.
He said: "By July last year all but 40 parents had been offered a place. I am as certain as I can be that all children will be placed as places are freed up as some parents with offers opt for independent schools instead."
The project has no plans to collect figures on how many children have been offered a place at their first-choice schools. Dr Birnbaum said that was a matter for individual local authorities.
Laura Warren of the National Confederation of Parent Teacher Associations said: "It is good news that the figures are falling but it is difficult to offer congratulations when there are still 3,000 children without places.
"Every child must know where they are going by August at the latest so they can prepare to move on and know which of their friends will be going with them."