Independent news outlet Mada Masr said Egyptian police arrested one of its editors on Saturday, amid an ongoing security crackdown.
Shady Zalat, 37, has worked since 2014 at the prominent website, which publishes investigations into corruption and security issues in Arabic and English.
Police raided Zalat's Cairo apartment without showing an arrest warrant, Mada Masr said.
Officers told his wife Zalat was being taken to the capital's Giza security directorate but Mada Masr was unable to confirm his whereabouts.
Zalat's arrest comes after Mada Masr published an article last week alleging that President Abdel-Fattah al-Sisi's son Mahmoud had been transferred to Moscow on a diplomatic posting.
His re-assignment from a senior intelligence post came after he had been criticised internally within the security apparatus, Mada Masr reported.
The article, which cited unnamed Emirati and Egyptian officials, gave details about the country's security agencies at a time when press freedoms in Egypt are shrinking.
It is unclear if Zalat worked on the piece.
Since Sisi led the military ouster of former Islamist president Mohamed Morsi in 2013, a crackdown has targeted journalists alongside dissidents and activists.
Since small-scale protests in September made rare calls for Sisi's removal, authorities have arrested some 4,000 people.
The demonstrations were triggered by viral videos posted online by an exiled businessman in Spain accusing the military's top brass of rampant corruption.
Egypt jails more journalists than any other country except China and Turkey, according to New York-based watchdog Committee to Protect Journalists.
Mada Masr is one of hundreds of websites blocked by Egyptian authorities in recent years and can only be accessed domestically via a virtual private network (VPN) application.
The publication called for Zalat's "immediate and unconditional release".