"I was really surprised by how similar Aboriginals and Irish people are, like in their mentality, particularly coming from that time," the 33-year-old actor said, noting both the Aboriginals and the Irish were fighting against oppression in their native lands.
In the film, based on a true story, O'Dowd plays manager to four young Aboriginal girls in a singing group called The Sapphires who are looking to secure a gig in Vietnam during the height of the war. But first he needs to get local audiences to look beyond the color of their skin.
"I think it's why the character as an Irish guy works quite well, because we're all part of the same team," O'Dowd said.
Aborigines are only 2.3 percent of Australia's 23 million people but are the poorest, tend to die a decade younger than other Australians and have higher rates of disease, joblessness and imprisonment. In 2008, the nation's prime minister issued an historic apology to Aborignes for the racial discrimination and injustices they endured for over 200 years.
The film is set during a time when mainly mixed-race Aboriginal children were routinely taken from their families by the government and placed with white families to assimilate them to white Australian culture. The practice lasted from 1910 until the 1970s, creating what became known as the "Stolen Generations."
"To be honest I knew very little about the stolen generation. You know, you get kind of glimpses, little details about the different struggles that oppressed communities have gone through, but this one was really brutal. Essentially, it was an ethnic cleansing. It was only in the `60s," O'Dowd said.
While the story takes place during a tumultuous period, O'Dowd - who may be best known for his role in "Bridesmaids" - sees it as more of a feel-good film.
"Sometimes these kinds of films about oppressed people can be very dour. Even if it's got a very interesting subject matter, it's lost because the film is too morbid to enjoy. And what I love about this, is we can do that and make it enjoyable," he said.
The film has already won numerous awards from around the world, including 11 AACTA Awards, which are the Australian equivalent of the Oscars - O'Dowd won for best lead actor. When it premiered at Cannes last year, it received a lengthy standing ovation.
"The Sapphires" was co-written by Tony Briggs, whose mother Laurel Robertson was an original Sapphires member. It is currently playing in U.S. theaters.
John Carucci covers entertainment for The Associated Press. Follow him at http://www.twitter.com/jacarucci