The Los Angeles County Coroner's office said Rooney died a natural death.
His burial was delayed following a dispute between family members on where he should be buried.
His will requested that he be buried at Forest Lawn Memorial Cemetery, but his wife Janice requested that his body be moved to another location.
Janice and his conservator, Michael Augustine, finally agreed on Hollywood Forever Cemetery. The settlement was approved by Judge Lesley Green.
The funeral was not open to the public.
Rooney was nominated for four Academy Awards over a four-decade span and received two special Oscars for film achievements, won an Emmy for his TV movie "Bill" and had a Tony nomination for his Broadway smash "Sugar Babies."