The two men and two women were detained after Gardaí searched two houses in Crumlin and Ashbourne yesterday morning.
It was part of an operation targetting the illegal streaming of TV content including pay per view products.
Six bank and credit union accounts with €84,000 in them have been frozen.
Another nine accounts have been limited - it is thought over €700,000 has been paid into them over the last three years.
Speaking yesterday, Detective Superintendent George Kyne of the Garda National Bureau of Criminal Investigation said: "This is an organised criminal enterprise where consumers are funding criminality and depriving genuine industry of legitimate revenue.
"Consumers are providing their payment details to unknown individuals and leaving themselves open to being the victims of fraud and/or data theft.
"The security around these devices and illegal streaming platforms exposes customers and leaves their home systems vulnerable.
"It is important that the public is aware of the impact of illegal streaming and its consequences."