Anatolia News Agency said the journalists were released on Monday due to time spent in custody and the likelihood the alleged crimes would be reclassified.
Ahmet Sik, Nedim Sener, Coskun Musluk and Sait Cakir were arrested on suspicion of plotting to overthrow the government through their alleged involvement in the ultra-nationalist Ergenekon movement, CNN reported.
Six other defendants remain in custody.
"This is not just about press freedom, this is about freedom of expression," Sik was quoted as saying after his release.
The Committee to Protect Journalists said Turkey has one of the highest numbers of journalists in jail in the world.