The dispersal order, which allows police to order people to leave an area, is authorised until 4pm on Sunday, having come into force at 4pm yesterday.
A spokesperson for the police said: "A borough wide dispersal zone has been authorised from 4pm hours until 4pm hours June 28.
"Officers will have additional powers under the Antisocial Behaviour, Crime and Police Act 2014 to direct person(s) to leave an area and not return within a specified period.
"This is a preemptive tactic to prevent antisocial behaviour and disorder which has occurred recently where unlicensed music events have been held."
Police have attended a number of large-scale parties across the capital which, with one Brixton event ending in violence.
A dispersal zone has been issued across the entire Lewisham borough as a preemptive move to combat illegal music events.
Police in Bromley also issued a dispersal order across the same period, however this applied to Queensmead Recreation Park only, rather than the borough as a whole.
Read about the Anti-social Behaviour, Crime and Policing Act 2014
Find out more about Dispersal powers