A police operation against the foreigners was launched after the office of Mayor Herbert Bautista received reports of their operation at an apartment in Don Enrique Heights, Barangay Holy Spirit.
The arrested Koreans were identified as Ra Su-bo, Yung Sungki, Ko Tae-myung, Bioung Jun-lee and Woaggi Min.
Quezon City Police District director Chief Supt. Richard Albano said the suspects faced charges for violating the Access Device Regulations Act of 1998 and Presidential Decree No. 1602, which prescribes stiff penalties for illegal gambling operations.
The raiding team secured a search warrant from the Quezon City Regional Trial Court Branch 77 before closing in on the suspects around 6 p.m. on Friday, said Supt. Ritchie Claraval, head of the City Hall police detachment.
Seized from the apartment were several computer sets and mobile phones.
Claraval said the owner of the apartment claimed no knowledge of the activities of the Koreans, who had been renting the place for several months.
The clients of the online gambling den were believed to be based abroad, the officer added.