"Blessed to be able to take Christopher out of the hospital last night. What a feeling of relief to know that he's going to be fine," Shriver tweeted. "Thank you for all your thoughts and prayers. The whole family, especially Christopher, felt your love," she added.
Christopher, the 13-year-old son of Arnold Schwarzenegger and Maria Shriver, was hospitalized and put in the ICU after suffering a collapsed lung and broken bones in the July 17 accident in Malibu.
Shriver complimented the medical staff that helped with her son's recovery: "I will forever be grateful to the amazing doctors, nurses and hospital staff in the ICU who helped my son." She added: "We were very lucky. Many patients and families we met have been there so long and have no end in sight. I pray for their recovery."
The former governor tweeted his own update: "I knew Christopher couldn't be stopped! Big thanks to all the doctors, nurses & staff at UCLA that helped him recover."