Leonardo DiCaprio has praised his Killers of the Flower Moon co-star Lily Gladstone.

Speaking with ABC News Breakfast Australia on Monday, the Oscar-winning actor, 49, revealed Martin Scorsese's decision to cast Gladstone as his onscreen wife, Mollie Kyle, was an easy one.

"As soon as Marty met her via Zoom, of course, because we were in the middle of Covid, he said, 'That is the person that I want for the role,'" DiCaprio shared, before adding that watching Gladstone transform into her character was "an amazing thing to witness".

"She really is the heart and soul of this movie at the end of the day," he gushed of the actress.

In the interview, Gladstone, 37, revealed she had all but given up on acting and was about to pursue a career in data analytics before getting the call from Scorsese.

"There are always that handful of really solid indie directors I will always take a call from, those just don't come by that often," she stated.

Recalling her experience working with Scorsese, she continued, "It's really hard to articulate what it's like working with somebody who lives and breathes cinema that way. It's a part of his DNA. And every time I get the opportunity to work with him, not only do I learn more about cinemas and art form, but I learn about what it is to be an actor."

Killers of the Flower Moon has grossed over $120 million (£98 million) at the global box office since its release on 20 October.