Affleck earned an Academy Award nod for his work in "The Assassination of Jesse James by the Coward Robert Ford" and garnered rave reviews for his performance in his brother Ben's 2007 feature film directorial debut "Gone Baby Gone."
People.com said Casey Affleck told reporters at the 80th annual Academy Awards Nominees luncheon Monday that being a dad "sort of changed everything."
"It's far and away the best thing that ever happened to me," he said. "I love being around the house and being with the kids everyday. Being an actor means that, if you're successful anyway, you can kind of work for three or four months out of the year and then you're home a lot of the time."
Casey Affleck is married to Summer Phoenix, actor Joaquin's sister.
The couple are parents to 3-year-old Indiana and a second son, who was born last month and whose name hasn't been announced yet, People.com said.
Oscars will be presented in Los Angeles Feb. 24.