In a decision published this week, the office said it had approved an application by the United States' Weta Holdings LLC to buy a third of the shares in Weta Digital.
That gives Weta a chance for big expansion to grow its visual effects business.
In September last year, the Herald reported Napster's Parker was yet to seek OIO approval to go further with its stake in Weta Digital.
Parker founded music file-sharing service Napster in 1999 and served as the first president of social media juggernaut Facebook in 2004.
Weta Digital is the visual effects arm of Sir Peter Jackson and Sir Richard Taylor's Wellington film empire.
It sits alongside post-production unit Park Road Post Production, equipment hire company Portsmouth Rentals, physical effects unit Weta Workshop and the WingNut Films production company.
Weta Digital says its ground-breaking work has earned it six visual effects Academy Awards, ten Academy Sci-Tech Awards and six visual effects BAFTA Awards in addition to the 34 Visual Effects Society Awards.
The OIO said it was involved due to the size of the deal US billionaire Parker proposed - "an overseas investment in significant business assets, being the applicant's acquisition of securities that results in a more than 25 per cent ownership interest in a person whose assets exceeds $100 million."
It went on further to detail how much of Weta Digital the billionaire can now buy: "The investment involves the acquisition of 5,569,620 new shares issued by Weta Digital, the value of whose assets exceeds $100,000,000, resulting in the applicant and associated persons owning almost one third of the shares."
Martin Wiseman of DLA Piper filed the successful application.
The office said the deal would enable Weta to grow: "Weta Digital is raising additional capital to grow its visual effects business."
It also named Sean Parker, calling him a US entrepreneur.
It did not have any qualms about giving approval.
Parker "has satisfied the OIO that the individuals who will control the investment have the relevant business experience and acumen and are of good character. The applicant has also demonstrated financial commitment to the investment."
In June, the Herald reported how Weta Digital is making original animated content for cinemas and streaming for the first time in its 25-year history.
Jackson and Fran Walsh plan to write, produce and direct several of the projects for Weta Animated.
"We are huge fans of animated storytelling in all of its forms, but it can be a long, protracted, and often costly way to make movies," Jackson said in a written statement six months ago.
Weta Digital was founded in 1993 to produce special effects for Jackson's film Heavenly Creatures and has grown exponentially as the movie industry has become more reliant on digital visual effects.
It's also been one of the rare filmmaking companies that has been able to continue functioning safely throughout the pandemic. In addition to the "Avatar" sequels, Weta Digital is also working on "Jungle Cruise" and "The Batman."
