The film, about a dysfunctional family racing to get their daughter to a kiddie beauty pageant, has been nominated for four Academy Awards, including Best Picture and Arkin for Best Supporting Actor as the heroin-addicted grandfather who is not going anywhere quietly.
"How do I describe him? He's irascible. He's opinionated. He holds nothing back. And trying to maintain a life of debauchery and fun that he's had all his life," he told Sunday Morning correspondent Jerry Bowen.
It's a role Arkin almost didn't get.
"They thought I was too virile for the part which is the best turn-down I've ever had in my life," he said.
"They" are husband-and-wife directing team Jonathan Dayton and Valerie Faris.
"I guess we weren't ready to see Alan Arkin as a grandpa," Faris said.
When they heard Arkin loved the script, they reconsidered.
"He's a great dramatic actor and can be very truthful in performance," Dayton said. "But he's also obviously an incredibly funny person. And we needed both those things."
"Yeah, and the warmth," Faris said. "There's a warmth to him that was essential in terms of relating to his granddaughter."
When "Little Miss Sunshine" debuted at the Sundance Film Festival, no one knew what to expect.
"I thought it was gonna tank. I said, 'Oh God! The intimate, small, wonderful little experience, they're not gonna — it's just too big a venue for it.' And then they went crazy," Arkin said.
Really crazy. Fox Searchlight grabbed the distribution rights for a record $10.5 million dollars. Since its release last summer, the movie has pulled in nearly $60 million at the box office.
The family road trip that is the story of "Little Miss Sunshine" starts here in New Mexico, Arkin's real-life home. A retreat and getaway for the Brooklyn-born boy who grew up in Los Angeles but feels more comfortable in the Southwest — far from either coast.
Arkin says it isn't just the natural beauty that energizes him.
"Well, I like to be in a place where there are different kinds of neuroses," he said. "In L.A., there's just one: Look at me! And in New Mexico, there's a lot of different kinds. So I get to move around them more fluidly."