"I'm Meghan Markle's brother," Thomas said in the trailer. "I'm the biggest brother of them all."
He then adds: “I told Prince Harry, I think she’s going to ruin your life. She’s very shallow."
In the clip, other stars included in the line-up are revealed, with former advisor to Donald Trump, Omarosa Manigault Newman, footy star Matt Cooper, Imogen Anthony, Survivor's Luke Toki, and Married At First Sight star Jessika Power all confirmed for the series.
Meghan has previously spoken about her fractured relationship with her family in the tell-all interview with Oprah Winfrey earlier this year.
“I don’t feel comfortable talking about people that I really don’t know. I grew up as an only child, which everyone who grew up around me knows, and I wished I had siblings," Meghan said.
"I would have loved to have had siblings,” she added.
Thomas will star alongside other names like Caitlyn Jenner, Dayne Beams, Bernard Curry, Ellie Gonsalves, and Josh Carroll, with the entire cast having been finally confirmed after weeks of rumours.
Big Brother VIP is set to air later this year, and if the trailer is anything to go by, fans can look forward to an explosive season.