Takei frequently appeared as a guest on The Howard Stern Show over the years, but officially joined the radio programme when Stern moved to SiriusXM in 2006.
In a new interview with Esquire, Takei said being offered a regular role in the controversial show came as a total surprise.
"I was kind of taken aback by that," Takei disclosed. "I didn't expect that invitation to come. I did the show a couple of times because I was peddling something. I thought that would be about the extent of it."
Takei added of Stern's offer: "He invited me to be a regular announcer, and I thought, 'Well, I'll try for a week'. And so he introduced me as the 'official announcer', and I had a lot of fun with it, but I'm an actor, not a radio personality.
"So I said, 'Let's compromise - I'll do you every quarter'. So that's the way it's been - every three months I pop up on The Howard Stern Show."
Takei has been involved in several of The Howard Stern Show's most memorable moments of the past six years, including his on-air arguments with former Star Trek co-star William Shatner over Shatner's treatment of the sci-fi show's cast.
He is currently competing in The Celebrity Apprentice, which airs Sundays at 9/8c on NBC.
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Listen to George Takei discuss his feud with William Shatner on The Howard Stern Show below (mature content):