In a statement, the Terminator, who is married to Kennedy Shriver's daughter Maria, notes the campaigning socialite's devotion to the Special Olympics was her greatest legacy.
He says, "Inspired by her faith in God... she was on a life-long mission to expand opportunities for those with intellectual challenges and to prove that they are capable of great achievements.
"Apart from her family, her greatest legacy is the Special Olympics, which started as a summer camp in her backyard in 1962, and has grown into a global movement and organization that has transformed the lives of hundreds of millions of people.
Kennedy Shriver, 88, died on Tuesday morning (11Aug09) in Massachusetts.
Former President John F. Kennedy's sister passed away on Tuesday morning (11Aug08) after she was checked in to Cape Cod Hospital in Barnstable, Massachusetts in a critical condition.
Shriver, mother of Schwarzenegger's wife Maria Shriver, was surrounded by her family, including her husband Robert Sargent Shriver, Jr and the actor-turned-governor himself.
Shriver is best known for her charity work raising awareness of the mentally disabled, after watching her sister Rosemary's struggle with mental illness. She also helped found the Special Olympics in the 1960s.
Shriver, the fifth of the nine Kennedy children, experienced poor health in recent years after suffering a series of strokes.
She is survived by her five children, Robert Sargent Shriver III, Maria Shriver, Timothy Perry Shriver, Mark Kennedy Shriver and Anthony Paul Kennedy Shriver, as well as 19 grandchildren.
Former President John F. Kennedy's 88-year-old sister has checked into Cape Cod Hospital in Barnstable, Massachusetts, and is surrounded by relatives, including her husband Robert Sargent Shriver, Jr and actor-turned-governor Schwarzenegger.
A family statement reads, "Eunice Kennedy Shriver is in Cape Cod Hospital in intensive care in critical but stable condition. Her entire family is with her - her husband, all her children and her grandchildren. The family is grateful for the prayers of her many friends.
A spokesperson for Schwarzenegger confirms, "He and Maria are both there with Mrs Shriver.
Shriver, the fifth of the nine Kennedy children, has suffered a series of strokes in recent years.
She lives in the clan's Hyannis Port compound, near to where her brother, U.S. Senator Edward Kennedy, is undergoing brain cancer treatment.
Eunice Kennedy Shriver, sister of the late President John F. Kennedy, mother of Maria Shriver and mother-in-law of Arnold Schwarzenegger, was injured Thursday in a head-on accident in Cape Cod, Mass.
Shriver, 79, broke her leg and required surgery after being taken to the Cape Cod Hospital.
"She's not dancing today but all her vital signs are stable, there were no complications from the surgery. She is resting comfortably," hospital spokeswoman Deborah Dougherty told Reuters Friday.
Earlier reports stated that Shriver may have suffered a head injury during the accident. According to local radio reports, witnesses saw her hit her head when her sports-utility vehicle collided with a pickup truck, in which she was not wearing a seat belt. Dougherty said she had no information on these reports.
The 20-year-old man who was driving the truck was cited for making an illegal left turn, while Shriver was cited for driving a vehicle with an expired registration, the radio report said.
This is the second time Shriver has been hospitalized in the past year. She spent seven weeks in the hospital last fall due to an infection after surgery to remove a benign pancreatic tumor.