The man, named by media as Waheed Ahmed, the son of a local councilor in Rochdale, northern England, was held by detectives at Birmingham Airport on suspicion of the commission, preparation or instigation of acts of terrorism, West Midlands Police said.
Police also said they had earlier arrested a 31-year-old man in the Rochdale area for the same offense.
"Officers are working to ensure the safe return of eight other people to the UK," police said in a statement.
The nine Britons were held by Turkish security forces on the Turkish side of the Syrian border on April 1. Waheed Ahmed's father, Shakil, issued a statement afterwards, saying he thought his son had been on a work placement in Birmingham and was shocked to learn of his arrest.
British security services estimate some 600 Britons have gone to Syria or Iraq to join militant groups, including the man known as "Jihadi John," who has appeared in several Islamic State beheading videos. About half are thought to have returned.
Last month, three male British teenagers suspected of planning to join Islamic State militants in Syria were arrested by London police after being deported from Turkey.
Their arrest came after three London schoolgirls entered Turkey earlier this year and are thought to have joined Islamic State in Syria, leading to criticism of British and Turkish authorities.