Akin Atalay was taken into custody at Istanbul's airport after arriving from Germany, said Cumhuriyet, which also saw nine of its staff arrested last week amid swelling concern over media freedom in Turkey.
The paper has in recent years taken a strong line against President Recep Tayyip Erdogan's ruling Islamic-rooted Justice and Development Party (AKP).
Atalay was targeted by a warrant that was part of a probe into "terrorist activities", and ushered into a police vehicle waiting for him on the tarmac.
Since the coup attempt, over 100 journalists have been arrested while 170 media organs including newspapers and broadcasters have been closed down, the Turkey Journalists' Association has said on its website.
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Turkey was ranked 151st of 180 countries in the 2016 World Press Freedom index published by Reporters Without Borders (RSF).
Speaking to AFP, RSF editor-in-chief Virginie Dangles described what she called "an unprecedented wave of arrests... under the guise of absurd accusations."
Last week, nine MPs from the opposition pro-Kurdish People's Democratic Party (HDP), including its co-leaders Selahattin Demirtas and Figen Yuksekdag, were detained pending a trial on terror charges expected to begin today.
Cumhuriyet's exiled former editor-in-chief, Can Dundar, fled to Germany earlier this year while appealing against a prison term for revealing state secrets.
Dundar was given nearly six years behind bars for a story about a shipment of arms intercepted at the Syrian border, which had prompted a furious Erdogan to warn Dundar he would "pay a heavy price".
"Cumhuriyet is the voice and breath of Turkey," said Huseyin Karabulut, who was among supporters in front of the paper's Istanbul offices.
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