"After much thought and careful consideration, we have made the difficult decision to divorce," the couple said in a joint statement. "We go forward with love and friendship for one another and a commitment to co-parenting our children, whose privacy we ask to be respected during this difficult time.
"This will be our only comment on this private, family matter. Thank you for understanding."
Affleck, 42, and Garner, 43, have three children together, daughters Violet and Seraphina, and son Samuel, and are often photographed out and about together in Los Angeles.
The couple co-starred in the 2003 action movie Daredevil, and married on the exclusive island of Parrot Cay in an intimate ceremony in 2005.
Less than three weeks ago, the family made a show of togetherness on an outing in Santa Monica.
There's said to be $150 million at stake in their divorce. According to People magazine, they've agreed to mediation.
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