Operation Avalanche saw 120 officers take part in early-morning raids today with drug warrants executed at 10 addresses across Barry, Dinas Powys and Penarth.
Local officers joined specialist officers from the Territorial Support Team and the dog section, as well as National Crime Agency officers for the operation.
Of the 11 people arrested on suspicion of drug offences, seven are men and four are women. Those arrested are aged between 19 to 51.
They are all currently in police custody. A quantity of cash and drugs were seized during the multiple raids.
Detective Inspector Dean Taylor said: “Operation Avalanche is a large-scale operation which has involved 120 officers and partner agencies.
“Tackling the supply of controlled drugs is a priority for us. We will not tolerate those making a profit from other people’s misery in the Vale of Glamorgan and we are committed to disrupting and dismantling these organisations.
“I would like to thank members of the public for their help in bringing these type of offenders to justice. If you have any information on drug dealing, please report it to us on 101 – we will act on your information. Alternatively you can call Crimestoppers anonymously on 0800 555 111.”