Shriver, who left her career at NBC after her husband, Arnold Schwarzenegger, was elected governor in 2003, will report on the "shifting roles, emerging power and evolving needs of women in modern life," the network said in a prepared statement.
Shriver described the career move in a blog post a "move forward into the next phase of my life."
"I'm going forward by doing what I love to do - telling stories that I feel are important to bring to life - and doing it in some new ways," she wrote.
Shriver, niece of President John F. Kennedy, filed for divorce from Schwarzenegger and moved out of the family's Brentwood home in 2011, after Schwarzenegger acknowledged keeping secret for more than a decade an extramarital affair resulting in a child.
Shriver worked on poverty and women's issues while first lady. She will be based in Los Angeles.
PHOTO CREDIT: Maria Shriver speaks at an event in Beverly Hills May 2012. AP Photo / Matt Sayles