The Trophy Wife actress, 35, and her husband Roberto Zincone have decided to split.
Malin and drummer Roberto married in an Italian wedding in 2007. In April, they welcomed their first baby together, a little boy named Sebastian.
"(Motherhood is amazing), the biggest love you have ever felt in your life," the star said shortly after having her child. "I go to my husband, 'I still love you, just this little one a little more.'"
A source told US Weekly that the split is "as amicable as can be", adding, "they want to do what's best for their son."
The couple started dating 10 years ago, and neither party is in a rush to file divorce papers.
"Honestly, Malin is not even ready to discuss it," a friend of the Rock of Ages beauty said. "It's a very sad time for her."
Just a few months ago, in September, Malin spoke lovingly about her musician husband. "We've never had one fight," she said. "We always talk things out."
Malin is currently starring as reformed party girl-turned-stepmum Kate Harrison in Trophy Wife.
She recently revealed that she identifies with the show because of her own "crazy" childhood.
"I grew up in a crazy, diverse, dysfunctional, amazing family — much like this family in the show," she told Elle.
"I have two stepdads, a step mum, half-siblings and step-siblings. Both of my stepdads and my dad were at my wedding. We have a picture of my mum and all of my dads. It's awesome."