Ninja streamed back on Wednesday, but is now on YouTube.
His channel has already reached around 24 million subscribers, with a maximum of 160,000 people watching him play Fortnite at some point during his first streaming on the platform.
He was playing against other famous players, Dr Lupo, TimTheTatman and Courage.
It is not yet clear whether Ninja has signed an agreement to play exclusively on YouTube, or whether it will also show up in places like Twitch. He still has 14 million subscribers on Twitch despite not playing on the platform for nearly a year.
Last August Ninja, whose real name is Tyler Blevins, left the streaming giant Twitch for a new platform called Mixer - reportedly for a huge contract with Microsoft Mixer owners.
However, Microsoft recently closed the platform and released players like Ninja to find new platforms.
Ninja is a huge presence on Fortnite - he even received his own skin in the game earlier this year.
