Markle, 36, who plays paralegal Rachel Zane on the series, will finish filming the show next month ahead of its eighth season, with plans of a royal wedding announcement before Christmas, the UK's Daily Star said.

"Meghan knows she can't really act at the same time as being a princess and is happy to make this career sacrifice," a source told the paper, adding that she'll instead focus on her charity commitments with Unicef.

Reps for broadcaster USA Network did not immediately reply to request for comment.

The couple, who have been the focus of intense tabloid speculation since they began dating in July 2016, officially went public at Prince Harry's Invictus Games in Toronto in September.

Markle has been based in Toronto, where Suits is filmed, since she began working on the show in 2011.

In September, she opened up on the public scrutiny surrounding the relationship in a cover story for Vanity Fair.

"We're a couple, we're in love," she told the magazine.

"I'm sure there will be a time when we will have to come forward and present ourselves and have stories to tell, but I hope what people will understand is that this is our time."

Rumours that the star would be quitting the show, and acting in general, first emerged in March.

"Even before Harry, she was starting to think about transitioning out of acting," a source told E! at the time. "She wants to focus on other worldly endeavours she is passionate about, like her philanthropy."

The series airs on Foxtel's Universal Channel in Australia.