The couple, who co-starred in the "Scream" film franchise, announced their separation in October 2010.
TMZ said Arquette cited "irreconcilable differences" in his divorce filing and requested legal and physical custody of their 8-year-old daughter, Coco.
KATE WALSH: Kate Walsh says she is leaving "Private Practice" at the end of the U.S. medical drama's upcoming sixth season.
TVGuide.com said Walsh made the announcement on Bethenny Frankel's new daytime talk show in an interview to air Wednesday.
"This is my last season for 'Private Practice.' ... It's been an incredible journey, an amazing ride. I'm hugely, hugely grateful," she said.
"It's been a long time being Addison," Walsh said of her character. "I feel incredibly grateful to [writer-producer] Shonda Rhimes and all the fans that have been there from Day 1 to now. I'm really excited about the last season."
Walsh's co-star Tim Daly announced last month he wouldn't be back for Season 6.
ALYSON HANNIGAN: Alyson Hannigan's publicist confirmed Tuesday the U.S. actress gave birth to her second daughter May 23.
People.com said Hannigan and her husband, actor Alexis Denisof, named their baby Keeva Jane Denisof.
"They are all doing well," Hannigan's representative told People.com.
The couple, who co-starred on TV's "Buffy the Vampire Slayer," are the parents of a 3-year-old daughter, Satyana.
"They're done," an insider said of the couple, who previously dated from 2006-07, then reunited last fall.
Asked on "Access Hollywood Live" Tuesday what her dating status is, Richards said only, "I'm friends with some very lovely men and everything's great!"
Richards has two daughters with her ex-husband, actor Charlie Sheen, as well as a baby girl she adopted as a single mom last year.