Thunberg was put in a large bus by local police along with other protesters who tried to block a major highway into The Hague.
Thunberg had joined a protest by hundreds of activists, and was detained when she joined a group of around a hundred people who tried to block the A12 highway.
That road has been blocked for several hours dozens of times in recent months by activists demanding an end to all subsidies for the use of fossil fuels.
At previous protests police drove detained protesters to another part of town, where they were released without further consequences.
Local police was not immediately available for comment on Saturday.
Reuters