Greta Thunberg said she has applied to register her name and that of the Fridays For Future movement she founded as trademarks.
The move would allow legal action against persons or companies trying to use her name or the movement's which are not in line with its values, she said.
Ms Thunberg, 17, launched the school strike movement in her native Sweden in 2018, a bid to put pressure on world leaders to step up measures to combat climate change.
She has catapulted to fame, speaking to a raft of world leaders and earlier this week she spoke at the World Economic Forum at Davos.
The teen activist posted about the move on Instagram on Thursday.
"I assure you, I and the other school strikers have absolutely no interests in trademarks. But unfortunately it needs to be done," she wrote.
Ms Thunberg said she had also applied to trademark "Skolstrejk for klimatet", school strike for the climate in Swedish - the wording on the placard she has held since she started her one-person protest outside the Swedish parliament in 2018, for which she missed school.
Her post continued: "My name and the #FridaysForFuture movement are constantly being used for commercial purposes without any consent whatsoever.
"It happens for instance in marketing, selling of products and people collecting money in my and the movement's name.
She added that her foundation, which has been registered but is not up and running yet, will seek to "promote ecological, climatic and social sustainability as well as mental health".
