Shriver tweeted on Tuesday, "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."
Christopher Schwarzenegger had suffered a collapsed lung and broken bones in the accident.
Arnold Schwarzenegger also tweeted on Tuesday saying, "I knew Christopher couldn't be stopped! Big thanks to all the doctors, nurses & staff at UCLA that helped him recover."
The accident came on the heels of a divorce battle between Schwarzenegger and Shriver.
The former governor amended his divorce filing on Monday, withdrawing a request to cut Shriver's spousal support. He also indicated he's willing to pay Shriver's attorney fees.
The couple separated after Schwarzenegger revealed he fathered a child with a housekeeper.
The Associated Press contributed to this story.