The operation, led by the Garda National Drugs Unit, unfolded following a number of months of investigation into an international drug trafficking racket believed to be spearheaded by a major Irish criminal living in Spain.
The crackdown began early yesterday morning when officers searched a number of industrial premises in Dublin and Meath which were understood to be used to store the drugs.
A team of officers then carried out a number of targeted searches of vehicles in and around the capital over the course of the next number of hours.
It is understood that hundreds of kilogrammes of cannabis herb and resin as well as thousands of ecstasy tablets and a quantity of what is believed to be cocaine, was recovered.
A machine gun is understood to be among six weapons which were also seized along with a number of vehicles.
The nine people who were arrested were reportedly aged between their late 20s and mid-40s.
They included Irish and Eastern European nationals.
Some of those arrested were reportedly customers of the drugs gang while others were key figures in the drugs operation.
Following their arrests, they were taken to five Garda stations around Dublin — Blanchardstown, Ballymun, Finglas, Clondalkin, and Store Street.