Cocaine worth some €930,000 was seized when gardaí searched a house in west Dublin on Tuesday.
Some 13kg of the drug was found when members of the Garda Drugs Unit arrived at the property in Tallaght.
A small number of ecstasy tablets were also seized during the search.
A man in his 40s was arrested in a follow-up operation and is being held at Ballymun Garda station under the provisions of Section 2 Criminal Justice (Drug Trafficking) Act 1996.
A Garda spokesman said the seizure was made as part of an ongoing operation into the sale and supply of controlled substances in Dublin city.
“Drug seizures play a critical role in targeting the livelihood of criminals and reducing their ability to carry out illegal activities,” gardaí said in a statement.