Kerry Kennedy walked arm-in-arm with her mother Ethel Kennedy after being found not guilty of driving under the influence of drugs.
Kennedy said outside of court, "I'm just very, very, very grateful that justice was done."
The Kennedy family was seated in the courtroom and erupted into cheers after the verdict was announced in White Plains, New York.
Kerry Kennedy was charged with DUI after a hit-and-run accident with a tractor trailer in 2012.
She testified during the four-day trial that she took an Ambien pill by mistake, and was unable to remember what happened. A doctor testified that Ambien can cause sleep driving or "zombiism."
Her lawyer, Gerald Lefcourt blasted prosecutors for charging her in the first place.
"You've got to wonder why an ill-advised prosecution like this was brought. Is it because of who the defendant is?" said Lefcourt.
Kerry is the daughter of the late Senator Robert Kennedy and the ex-wife of New York Governor Andrew Cuomo. They have three grown daughters, and daughter Cara walked with her mom and grandmother after the verdict.
Meanwhile, does 54-year-old Kerry have a new boyfriend? His name is Trevor Donovan. He's a 35-year-old actor best known for his role in 90210. Trevor is 19 years younger than Kerry. His manager told the London Daily Mail that they've been friends for years and got even closer when kerry called him after her DUI arrest.