The haul - one of the largest taken in Glasgow - was discovered by crimebusters who swooped on the property in Summerston.
Police arrested a 43-year-old man in connection with the discovery.
Specialist officers also seized computers, hard drives, IT equipment and dozens of discs, after apprehending the man.
Last night, he was being held at London Road Police Office while further investigations were carried out.
Officers acting under warrant raided the flat in Carbost Street, in the city's Summerston area, at around 8.30am yesterday.
The man was arrested in connection with alleged copyright offences.
The arrest is believed to involve the illegal downloading of music from internet sites.
It was part of Operation Salang, aimed at disrupting the alleged illegal activities of organised crime groups.
The arrest was the culmination of a lengthy intelligence-gathering operation involving a number of officers and lasting a period of several months.
Sergeant Chris Hoggans said: "This successful operation demonstrates our commitment to tackling counterfeit crime.
"With the continued help, support and co-operation of our local communities, we will continue to target this type of criminality.
"People think there is nothing wrong with buying counterfeit goods and they think they are saving money.
"However, often the proceeds can be used to fund serious and organised crime."
The 43-year-old is expected to be released on an undertaking.
Research by the British Recorded Music Industry in 2010 revealed that 7.7 million people in the UK had illegally downloaded music - a concept known as file sharing.
The group claimed that more than three quarters of music downloaded in the UK is illegally obtained, with no payment to the musicians, songwriters or music companies producing it.