Winfrey sat down with Nancy O'Dell on Thursday and opened up about speaking with the couple.
"I had no idea it would have the reverberating impact that it has had and continues to have," she told O'Dell during the launch of The Nancy O'Dell Channel on TalkShopLive. "I did a lot of preparation for that. It was really important to me that what we put out there in the world was put out into the world at the time that everybody could see it and that things didn't leak and that things weren't misconstrued before the actual interview happened."
During the March 7 interview, which aired on CBS, Meghan talked about how she faced racism and said the royal family had "concerns" over the skin color of her son, Archie. Meghan, who is pregnant with her second child, also told Winfrey she felt isolated and when she tried to seek help from the palace's human resources department for suicidal thoughts, she did not receive it.
The royal family has kept quiet about the interview, except for a brief comment from Prince William denying that the family is racist. "We are very much not a racist family," he said.
Buckingham Palace said in a statement that the family was "saddened" to learn the extent of the challenges faced by the couple.
"The issues raised, particularly that of race, are concerning," the statement said. "While some recollections may vary, they are taken very seriously and will be addressed by the family privately."
Winfrey told O'Dell that she had texted Harry and Meghan prior to their sit-down — which lasted 3 hours and 20 minutes — to ask them what their intentions were with doing the interview.
"Our shared intention was the truth," Winfrey said. "They wanted to be able to tell their story and tell it in such a way that allowed them to be as truthful as possible."
When asked if she was surprised at how open the couple was, Winfrey responded, "I was surprised."
"I'm like, 'What? You're going there? You're going all the way there,'" she added.
Winfrey said she thinks her interview with the Duke and Duchess of Sussex was so "powerful" because they were willing to be vulnerable.
"What makes it powerful is when you have somebody else who is willing to be as open, as vulnerable, as truthful as they were," she said. "The reason the interview was what it was because they answered the way they did."
This article was originally published on NBCNews.com.