Mamun Rashid, from east London, was arrested on Thursday after he arrived on a flight to Heathrow Airport.
It came after Turkey announced it had sent back a British Isis suspect.
On Sunday the Metropolitan Police announced Rashid had been charged with preparation of terrorist acts under the Terrorism Act 2006.
He is now due to appear at Westminster Magistrates’ Court in central London on Monday.
Neither the Home Office nor the police have issued any further details about the offence other than to say it is “Syria-related”.
Turkey has accelerated attempts to deport suspected foreign fighters to their respective countries after Donald Trump criticised European leaders for failing to take back militants caught in the battlefields of Syria and Iraq. .
Last month the US president threatened to “drop” captured Isis fighters on the UK border if the government does not start repatriating them from Syrian camps.
The UK government has repeatedly refused calls to repatriate British men, women and children held in Syria, arguing it is too dangerous.
Several suspects, such as Bethnal Green schoolgirl Shamima Begum, and 24-year-old “Jihadi” Jack Letts, have been stripped of their British citizenship.
Two suspected British Isis terrorists, the “Beatles” Alexanda Kotey and El Shafee Elsheikh, have been taken from Syria into US custody amid fears they could escape during the Turkish invasion of northeastern Syria.