A “sensational” attack would have taken place had the arrests not been made, according to police in President Erdogan’s country.
A staggering 150 kilograms of explosives, two automatic rifles and other material were found with the four, the state news agency reported.
Anadolu Agency said Thursday the suspects were detained in an operation in Gaziantep, near the border with Syria.
It was not made clear if the suspects had travelled over the border from Syria, the Anadolu Agency reported.
Last year, Turkey suffered a series of deadly attacks carried out by IS or Kurdish militants.
The latest large scale assault was a massacre on New Year’s Eve at Reina nightclub in Istanbul.
Abdulkadir Masharipov is believed to have mounted the assault which left 39 people dead.
Last week, 750 people with alleged IS links were detained after a major police operation.