The Toronto-based American actress, who stars in the hit US TV show 'Suits,' revealed the pair were introduced in July 2016 by mutual friends in London.
"We're two people who are really happy and in love," Markle told Vanity Fair. "We were very quietly dating for about six months before it became news, and I was working during that whole time, and the only thing that changed was people's perception.
She added: "Nothing about me changed. I'm still the same person that I am, and I've never defined myself by my relationship."
In November, Prince Harry ended weeks of speculation and confirmed that they were in fact an item in a statement released by Kensington Palace.
He condemned the "wave of abuse and harassment" his girlfriend had faced from media outlets before adding that he was worried for her safety.
The move was a departure from the usual sharply choreographed media announcements from the British royal family.
The palace rarely puts out such statements, only doing so in recent years to keep the paparazzi from getting too close to Prince George and Princess Charlotte, the children of Harry's brother, Prince William.
The brothers have been much more open about their personal lives than their royal predecessors. Recently they spoke publicly about their mother, Princess Diana, on the 20th anniversary of her death.
'The rest is noise'
Markle, 36, shed light on the media frenzy that has engulfed her life since she embarked on the year-long relationship, admitting it can be difficult at times.
"It has its challenges, and it comes in waves -- some days it can feel more challenging than others," she told the magazine. "And right out of the gate it was surprising the way things changed. But I still have this support system all around me, and, of course, my boyfriend's support."
In the interview, Markle also claimed not to read any articles about herself, a strategy she may have picked up from the Duchess of Cambridge, Prince William's wife, who is said to have adopted this tactic when handling the media's glare.
"I don't read any press. I haven't even read press for 'Suits.' The people who are close to me anchor me in knowing who I am. The rest is noise," she said.
The interview will likely do little to quell swirling rumors around the couple regardless of the fact that they largely stay away from the cameras.
"We're a couple," Markle said. "We're in love. 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. This is for us. It's part of what makes it so special, that it's just ours. But we're happy. Personally, I love a great love story."