It could be 100 years before the Met Police has the same ethnic mix as the population it serves, the force said.
Currently 14% of Met officers are from black, Asian and minority ethnic backgrounds, but the 2011 Census shows 40.2% of Londoners identify as BAME.
As a result the force says it wants to recruit 250 extra BAME officers a year.
It comes as the force announced how it has changed since it was branded "institutionally racist" following Stephen Lawrence's murder in 1999.
The force said its prediction that it could take 100 years to have a workforce that reflects Londoners would happen if it did not take further steps to "attract and retain" BAME officers.
Eighteen-year-old Lawrence was set upon by a gang, stabbed and left to die in Eltham, south-east London, on the evening of 22 April 1993.
The bungled initial investigation into his death was hampered by claims of racism, corruption and incompetence, and it took nearly 20 years for two of his five or six killers to finally be brought to justice.
David Norris and Gary Dobson are both serving life sentences while the rest have evaded justice.
Met Police Commissioner Cressida Dick said the Macpherson report into the aftermath of his murder had "defined my generation of policing" but she said she did not believe the force was now institutionally racist.
"We are ambitious for the future, we are not going to forget Stephen or his legacy and we will continue to educate our officers about why it is that this police service does what it does now, and how that comes from the Stephen Lawrence Inquiry," she said.
The latest report from the force's HR found 16% of PCs were BAME, and fewer than 10% for higher ranks. The proportion is 4% for chief officers.
BAME officers and staff are also more likely to resign from the force or raise grievances.
Since 1999, BAME officers have increased from 3% to 14%, while last year 30% of new recruits were from that background.