When asked why he thought Meghan and Harry had quit their royal roles, Thomas spilled: “I think she just wants to go back to Hollywood.”
The Sussexes completed their final royal engagement at last week's Commonwealth Day service in London.
They are due to officially step down as senior royals on March 31.
Meghan’s first on-screen appearance was in an episode of daytime soap opera General Hospital in 2004, where she played a small role as a nurse.
She went on to secure guest roles in several TV shows, including Century City, The War at Home and CSI: New York.
The Duchess was also a a “briefcase babe” on the US version of Deal or No Deal.
Meghan’s career changed markedly when she joined the Suits cast in 2011, where she played Rachel Zane for seven of the nine seasons.
Earlier this week, Meghan Markle's brother Thomas Markle Jr spoke out to say he isn't a fan of his sister's acting abilities.
Speaking to Express.co.uk, the Duchess of Sussex's estranged brother revealed what he really thinks of Meghan and her expected return to Hollywood, saying she "isn't A-list".
When asked how people would react if the Duchess returned to Hollywood, he replied: “Some people will probably go see her.
“I say this gingerly here, I guess, she’s not an A-list actress. She was a character in a series on cable.”
Meghan starred in law drama Suits for seven years and stepped down from her role as Rachel Zane before marrying Prince Harry in May 2017.
However, it's clear her brother Thomas was never a fant.
“I think I watched it once or twice - I saw it a couple of times," he said.
“She had a few good lines in it, a few good scenes.”
Mr Markle told how Meghan’s high profile as the Duchess of Sussex would “open a few more doors for her”.
He added: “Now I think she will be given more opportunity, with being who she was, so I think it might open a few more doors for her.
“But she’ll get some good movie roles, she’ll do alright.”