Sources confirmed the planned sale to the Orlando Sentinel on Tuesday. It was originally reported by TheWrap.com, a news website covering the entertainment industry.
Universal Orlando spokesman Tom Schroder refused to comment on the reports.
Philadelphia-based Comcast bought a controlling interest in NBCUniversal in January.
The planned purchase isn't too much of a surprise since a March Securities and Exchange Commission filing noted that Blackstone had offered to sell its share of the theme parks back to NBC Universal Inc.