Ninja, who recently switched from Twitch to Mixer, said on his stream he's been negotiating with Adidas for over a year, and the sides finally reached an agreement.
Adidas released a statement to Edgar Alvarez of Engadget, saying the deal with Ninja is meant to illustrate its commitment to "creators who show dedication to excelling in their field" and gaming culture as a whole. He becomes the brand's first gamer under contract.
In April, the 28-year-old Detroit native was named one of the 100 most influential people in the world by Time.
"At the end of the day, Ninja is an absolute legend, and someone to whom we owe a lot for making gaming what it is today," Pittsburgh Steelers wide receiver JuJu Smith-Schuster wrote in Time.
"No shortcuts. Only long days. Never let anyone tell you that you can't catch your dreams," Ninja wrote on Twitter. "Choose your path. Put the TIME IN. I'm humbled, and excited, to officially announce my partnership with Adidas Originals."
Terms of his contract with Adidas were not immediately released.