She was detained at a house in Lambeth on Tuesday where officers also carried out a search of the premises.
It was part of a Counter Terrorism Policing London investigation into social media posts.
The woman has been bailed until April.
She was detained at a house in Lambeth on Tuesday where officers also carried out a search of the premises.
It was part of a Counter Terrorism Policing London investigation into social media posts.
The woman has been bailed until April.