Almost 300 police officers swooped to tackle a suspected drug dealing ring in a string of dawn raids at more than 30 properties in and around Sutton, Merton and Wandsworth.
Twenty-two people were arrested on suspicion of conspiracy to supply class A drugs.
Surrey Police led the operation, which involved 270 officers including dog handlers, detectives and rapid entry teams, after receiving intelligence suggesting large scale drug dealing was going on from a number of linked addresses.
Those arrested have remain in custody as questioning continues. One of those arrested was also detained on suspicion of firearms offences.
Superintendent Jerry Westerman said: "Operation Beet has yet again shown how successful Surrey Police is in identifying and dismantling suspected networks of drug dealers who attempt to supply illegal substances in our county.
"It is widely accepted that class A drug abuse destroys communities. Not only are those dependent on drugs harming themselves but anyone who has been a victim of a crime as a result of a user needing to fund their habit are also affected.
"Although the majority of the warrants executed this morning were in the borough of Reigate and Banstead, we also identified the need to target suspected dealers at addresses in London.
"This sends out a stark warning to anyone thinking of coming into Surrey intent on committing offences that we can, and will, put an end to the misery caused by drugs."
Anyone who has information about drug dealing in their community can contact police on 101 or the charity Crimestoppers on 0800 555 111.