The number of people who call themselves Londoners is set to hit a new record high of more than 8.6m this year.
The capital's population is expected to top the previous record set in 1939, at the start of World War Two.
The latest growth is being fuelled by a rising birth rate among existing Londoners as well as an influx of newcomers.
Official figures from the Office of National Statistics also predict a population of more than 10m by 2029.
The forecasts raise questions about the inevitable pressure on housing, schools, transport and the health service.
London's population peaked at 8,615,000 in 1939 but declined in the post-war decades. The ONS believes the figure will hit 8,641,000 at some point this year.
London mayor Boris Johnson said the rising birth rate should spark a national debate about population growth: