"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 announcement comes just one day after the couple's 10th wedding anniversary on Monday. The duo said this "will be our only comment on this private, family matter."
Garner, 43, and Affleck, 42, married in 2005 and have three children, Violet, 9, Seraphina, 6, and Samuel, 3.
The pair met in 2001 on the set of "Pearl Harbor" and went on to star alongside each other in the 2003 film "Daredevil."
Years later, Affleck admitted that he fell in love with Garner on the set of the film.
"That’s where I found my wife," he told Playboy magazine. "We met on Pearl Harbor, which people hate, but we fell in love on 'Daredevil.'"
They got engaged in April 2005 and married two months later in a private ceremony in the Turks and Caicos while Garner was four months pregnant with their daughter Violet.
Garner has been open about how having children changed their marriage.
She recently told Yahoo! Parenting, "You just go on a ride together because you don’t know who you’re going to be when you first have a baby and you don’t know who [your partner] is going to be. You have to just hang in there while you figure it out -- and have a lot of patience for each other."
Last year, she told InStyle, "When we had our first [child], we had only been together a year. We were babies. It happened so fast, I hardly remember what we were like before the kids got here."
She also told the magazine that she and Affleck had a "mindful" marriage.
"You can't expect to be courted all the time, and I don't want to court him right now; I don't have the energy!" Garner said. "But we're definitely in a very mindful place where we're making an effort to be together, do things at the same time, and be loving."
For his part, Affleck made headlines when he accepted his best picture Oscar in 2013 and thanked his wife for "working on our marriage," adding "there's no one I'd rather work with."