The court ordered the five jailed on Monday, just one day after two prominent investigative journalists were jailed for the same plot.
Police detained the two men, Nedim Sener and Ahmet Sik, along with eight other people — most of them journalists — on Thursday after raiding their homes.
International rights groups and Western governments have expressed concern over the arrests, but prosecutors have insisted the journalists were not detained because of their work.
The raids and detentions were part of Turkey's investigation into the Ergenekon network, a secularist group authorities allege is planning bombings and other attacks to discredit the government and trigger a military takeover.
Sik co-wrote a book about the crackdown on Ergenekon, while Sener is an investigative reporter for a major Turkish newspaper and wrote a book on the murder of journalist Hrant Dink.
Several thousand people demonstrated in Istanbul and Ankara Friday following the arrests, protesting what they called an increasing lack of press freedom under the government of Prime Minister Recep Tayyip Erdogan.
Turkish authorities have detained more than 300 people, including other journalists, academics, politicians and retired military officers, as part of the investigation into Ergenekon.
Critics say the detentions are an effort to silence the opposition.