The Star Trek actor first hinted that he was in talks for a role on the CBS drama in September 2011.
The official CBS Twitter account announced the casting, posting: "Can u say HAWAII FIVE-OH MY?! The incredible George Takei will appear as Chin's Uncle this season!"
The role will see Takei appear alongside Lost's Daniel Dae Kim - who plays Chin Ho Kelly - and his former Heroes co-star Masi Oka, now a Hawaii Five-0 series regular.
The 75-year-old star previously told Digital Spy that he was a fan of the revamped Hawaii Five-0, having appeared on the original series in 1975.
"I'm addicted to... Hawaii Five-0," said Takei. "Dramatic shows are the ones that I am attracted to."
The third season of Hawaii Five-0 continues on Mondays at 10/9c on CBS, with Takei's episode slated to air in December. In the UK, the series airs on Sky1.
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Watch a clip from Hawaii Five-0 below: