MacFadyen, 47, received the award for outstanding supporting actor in a drama series for his performance in HBO's Succession.
As he accepted his award Monday he first thanked the Television Academy.
"I'm deeply flattered and thrilled to bits," he told the crowd. "Its a pleasure and a privilege to play this bonkers gift of a role."
MacFadyen thanked the team behind the series as well as the "most supremely talented crew and cast I can imagine."
Nicholas Braun (Succession), Billy Crudup (The Morning Show), Kieran Culkin (Succession) Park Hae-soo (Squid Game), John Turturro (Severance), Christopher Walken (Severance) and Oh Yeong-su (Squid Game) were also among the nominees for the 2022 outstanding supporting actor in a drama series prize.
Macfadyen is now a two-time Emmy nominee and first-time winner for his involvement in Succession as Tom Wambsgans.
PATRICK T. FALLON/AFP via Getty Matthew Macfayden
Though the actor is English, he has previously admitted that playing an American is "a great liberation."
"My voice goes into a different register. It's like putting on a big hat or a very colorful suit. We're suffused with American culture in the U.K. Everybody is, with films and TV. So stuff goes in, and then you get an opportunity to do a role like this, and it just sort of comes out without you knowing it," he told Backstage in August.
"I'm a great believer in that. It's odd, acting — because you can do research, but so much of the work is done without you really knowing it, as long as you keep your imagination open," he continued. "When I work on a part, I don't sit down and say, 'Let's do this and this.' I don't try and commit to things or make decisions until the last minute. As an actor, you're constantly observing, watching, like a magpie; you think, Maybe I could use that — that little thing I saw someone do on CNN."
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Filming for season 4 of Succession began in June.
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The 74th Primetime Emmy Awards are being broadcast live on NBC from the Microsoft Theater in Los Angeles.