The 22-year-old painted a red handprint over his mouth to stand in solidarity with murdered and missing Indigenous women.
According to the Native Hope organization, a red hand over the mouth has become a symbol of the growing MMIW movement.
"It stands for all the missing sisters whose voices are not heard," read a description on the Native Hope's website. "It stands for the silence of the media and law enforcement in the midst of this crisis. It stands for the oppression and subjugation of Native women who are now rising up to say #NoMoreStolenSisters."
The show, which follows four Indigenous teenagers in rural Oklahoma as they try to get to the mysterious and faraway land of California, received four Emmy nominations, including Outstanding Comedy.
Woon-A-Tai has made history as the first Indigenous nominee ever in a lead acting category at the Emmys.
"Not a lot of Native actors, creatives, artists get to be on stages like these," he said when he was nominated at the Critics' Choice Awards this year. "To be on stage and be representing our people every day, it's an honor."
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