Detectives swooped on 22 homes in the Liberton, Gilmerton and Craigmillar areas of Edinburgh on Friday.
More than 170 officers, from local police teams and the Specialist Crime Division’s Organised Crime and Counter Terrorism unit, were involved in the Operation Amyloid raids.
Police Scotland said 2.2lb (1kg) of heroin with an estimated street value of £100,000 was recovered at a home in Niddrie.
Further dealer quantities of heroin, drug paraphernalia and 9oz (250g) of cannabis were seized along with around £5,000.
Fourteen men, aged between 21 and 48, and six women, aged from 19 to 44, are expected appear at Edinburgh Sheriff Court. A 27-year-old woman has also been reported to the procurator fiscal.
Detective Chief Inspector Kenny Gray said: “This operation has been the culmination of months of intelligence gathering, but I want to make it clear that it isn’t over.
“Police Scotland will continue to target those involved in serious and organised crime throughout Edinburgh and to send a message that these sort of offences will not be tolerated.”