Markson shared the news via an Instagram post on August 7.
"It’s official! @bigbrotherau VIP cast officially announced today ! I’m very proud to be representing not 1,not 2,not 3 not 4 but 5 of the housemates @omarosa & @therealthomasmarklejr from the US plus @jessika_power @coopsmatt & the enigmatic @imogen_anthony," he said in the caption. "Call me if you need a celebrity for your next project or business venture. Email & phone number in bio."
The Markson Sparks talent agency has been around for 30 years, and they tout themselves as "Australia‘s premier publicity, celebrity management and events organisation."
In a teaser video for the new season of the reality competition series, Thomas Jr. made it clear that he wants everyone to know his famous ties.
"I'm Meghan Markle's brother, I'm the biggest brother of them all," he declared in his introduction clip. "I told Prince Harry, I think she's going to ruin your life. She's very shallow."
He'll be joined in the Big Brother house by 11 other individuals, including Omarosa, Caitlyn Jenner and athlete Dayne Beams.
The Duchess of Sussex isn't on good terms with any of her siblings, and none of them were invited to her 2018 wedding.
"I’m not bitter, just baffled. It’s hurtful given how close we once were," he previously admitted of the situation. "I’m confused and a little distraught because here is a person knowing the position she’s in and knowing the scrutiny she’s under and yet she has forgotten her flesh and blood."
The mom-of-two is also estranged from their father, Thomas Markle Sr., though he sent his daughter flowers for her 40th birthday on August 4.