The woman, identified as Yasmin Ahmed, was arrested by a special team of Kerala police from Indira Gandhi International airport in Delhi when she was about to leave the country for Kabul on Sunday, police said.
She allegedly had close connections with Abdul Rashid, a native of Kasaragod, who is the prime suspect behind the 21 missing youths from the state.
She was brought in Kasaragod on Monday and produced before a local court after detailed interrogation, a senior police official said.
"We took her into custody from New Delhi and brought her here yesterday. She was charged under various sessions of the Unlawful Activities (Prevention) Act (UAPA). A court here later remanded her to judicial custody," said Kanhangad Deputy Superintendent of Police Sunil Babu.
The woman is suspected to be the second wife of Rashid and is believed to have played a key role in the alleged recruitment of state youths to Islamic State, the official added.
Chief Minister Pinarayi Vijayan, referring to reports that some Keralites had joined Islamic State, had informed the assembly on July 11 that 21 persons were missing from the state.
Among them, 17 were from Kasaragod and four from Palakkad as per preliminary information available, he had said.
As per media reports, these people had gone to Syria and Afghanistan and were in Islamic State camps, he said.