In a joint statement released Monday night, the couple said they are living apart while "they decide on the future of their relationship."
"This has been a time of great personal and professional transition for each of us. After a great deal of thought, reflection, discussion, and prayer, we came to this decision together," the statement said.
Schwarzenegger and Shriver said they plan to continue to "parent their four children together."
"They are the light and the center of both of our lives," they said in the statement.
The couple married in 1986.
Both Schwarzenegger and Shriver said they consider this a private matter and plan to not release any further comment.
"We ask for compassion and respect from the media and the public," the statement said.
Before they became the governor and first lady of California in 2003's recall election, Schwarzenegger and Shriver led lives far from politics but still very much in the spotlight.
Prior to Schwarzenegger being elected governor, Shriver was a broadcast journalist for NBC News. She is a member of the Kennedy family - her mother was the late Eunice Kennedy Shriver, the sister of former President John F. Kennedy.
Her father was Peace Corps founder and former Democratic vice presidential candidate Robert "Sargent" Shriver Jr., who died earlier this year.
Schwarzenegger was a former body builder and action film star who appeared in films like the "Terminator" and "True Lies."
Campaign and Election Run
In an interview on "Good Morning America" in 2006, Shriver never imagined she would be in the middle of political world in California.
"When I married Arnold, politics wasn't really where I thought we were going!" she said in the 2006 interview. "Nancy Reagan gave me very good advice. She said, 'Do whatever you want, because you're going to get criticized anyway.'"
But it wasn't always a smooth ride to the top of California's highest political office.
During his run for governor in the recall election to replace then Governor Gary Davis in 2003, the Los Angeles Times reported that six women alleged that they were fondled or groped by Schwarzenegger sometime between 1975 and 2000.
At the time, Schwarzenegger publicly admitted he had "behaved badly" and apologized if he had offended anyone. Shriver stood by her husband amid the allegations the Times reported at the time.
Despite marking their 25th wedding anniversary on April 26, it appears that the couple has been living different lives for some time according to the Los Angeles Times.
Shriver has moved out of the couple's home in Brentwood.
Twitter updates to Shriver's account does not make mention of the anniversary.
In a March 28 video posted on YouTube, Shriver said, "It is so stressful to not know what you're doing next," the Times reported.
Through the years, Shriver has been running the annual women's conference that's billed as the "nation's premier forum for women."
She is credited the major makeover of the California Museum, according to the Associated Press.
Since leaving office in January, Schwarzenegger has indicated his intent to return to his acting and entertainment business roots.
He is set to return with a new animated series called "The Governator."
Schwarzenegger spokesman Alan Mendelsohn told the Associated Press last week that the actor is looking into starring the film, "Cry Macho."
The Associated Press contributed to this report.