The 32-year-old British royal and 35-year-old American actress were spotted holding hands following a dinner date Wednesday, according to The Sun.
Prince Harry and Markle stepped out in coordinating outfits for a meal at Soho House in West London. Sources said the couple have been "inseparable" over the past few weeks.
"Meg is not filming in Toronto at the moment so she is free to spend all her time with Harry," an insider said.
"They've taken things to the next level. They're practically living together. She cooks for him, he pops out to the gym and they're just enjoying hanging out," another source added.
Prince Harry and Markle were first linked in October, and confirmed their relationship the next month after the actress faced racist backlash. Markle's Suits co-star Patrick J. Adams weighed in on the couple during an interview this week with Access Hollywood.
"She's like a sister to me -- we've been like brother and sister for so long -- so I'm just super happy for her that she's found someone that she seems to really be into," the actor said. "We don't talk about it much."
"I would love to do that thing that a big brother gets to do where you get to actually meet the guy -- vet him a little bit -- I think we should go through that process," he added. "Just make sure he's up to speed."
Markle plays Rachel Zane on Suits, which airs Wednesdays at 10 p.m. ET on USA. The series is in its sixth season and co-stars Adams, Gabriel Macht, Rick Hoffman, Sarah Rafferty and Gina Torres.