Officers in Soho made a series of arrests last night before raiding dealers' home addresses in dawn swoops this morning.
It is the second operation of its kind aimed at cleaning up the lively area of the West End, which is popular with tourists and partygoers.
Officers have worked for several months to prepare for the crackdown, identifying individual drug dealers.
"My cause celebre is tackling this open drug dealing in the area because it's very closely connected to other serious acquisitives (for example, robbery and theft from the person) and violent street crime. It's a menace to the public in the area."
Mr Southworth said the scene is "quite chaotic", being run as an open market rather than controlled by one gang.Around 80 to 100 officers were taking part in the operation.
It follows a previous operation in which 30 drug criminals were arrested and convicted.
More top news
Hackney's Idris Elba could become the next James Bond, it has been reported.
Hollywood legend Joan Collins OBE brought some much needed Christmas cheer to families supported by children's hospice Shooting Star Chase.
London mayor Boris Johnson is backing Olympics supremo Seb Coe as his replacement.