The actor won the Emmy for Outstanding Supporting Actor in a Limited Series or Movie at the 73rd annual awards.
Peters beat out Thomas Brodie-Sangster (The Queen’s Gambit), Paapa Essiedu (I May Destroy You), as well as Hamilton co-stars Daveed Diggs, Jonathan Groff and Anthony Ramos.
"Thank you to the Academy. My fellow nominees, you guys were all incredible this year," Peters said while accepting the award. "I got to thank my mom and dad for getting me out to L.A. You guys are crazy for doing that, but we're going to drink tonight."
He went on to give an enthusiastic thank you to fellow Mare of Easttown star Kate Winslet for, well, "being Kate Winslet!"
"I especially want to thank everyone who watched my show," he continued. "This is a dream come true for me tonight and it wouldn't be possible without you. So thank you."
Mare of Easttown, as well as WandaVision, marked a breakthrough year for the actor, who was previously known for his performances on multiple seasons of American Horror Story. For the actor, the HBO limited series and working opposite Winslet was a chance to show something different.
“I just love to go big. I think it’s so fun, and some of my favorite actors are very big actors. But this was an opportunity to go the opposite direction,” Peters told ET in August. And given the nature of Mare, “it was an opportunity to take everything down a notch and be a little more still and subdued.”
In total, Mare of Easttown was nominated for 16 Emmys, including Outstanding Limited or Anthology Series. Prior to Sunday, it took home the prize for Outstanding Production Design for a Narrative Contemporary Program (One Hour or More) during the Creative Arts Emmys.