The South London-born star scooped the award for Best Actor at Sunday night’s star-studded affair for his part as Sir Winston Churchill in Darkest Hour.
Morgan and co-presenter Susanna Reid opened Monday’s show by giving viewers a quick rundown of what happened at the Los Angeles ceremony, but the Best Actor winner was the main talking point.
The outspoken broadcaster said: “It was interesting, we call Gary Oldman a British winner, but he just made a big speech about America and about being American, having American kids. Lives in America.
“I was waiting for him and thinking, ‘Come on mate, you’re playing Sir Winston Churchill, at least give us a scrap. He mentioned South London, but he didn’t grab the British thing.”
Irate, he continued: “He basically stood there and was like, ‘I’m so grateful to America.’ Wait, it was this country that empowered you, Gary Oldman.
“You’re playing one of the great British leaders of history,” he jested.
When Reid asked if he was “accusing him of being a traitor”, Morgan shunned his co-host for “putting words into his mouth”.
He added: “I think Gary Oldman is a very brilliant actor but you should never forget your roots. When you win those big awards, you’re there for Britain.”
Good Morning Britain airs weekdays from 6am on ITV.