The Duke of Cambridge, 34, and Lady Gaga, 31, have joined forces to promote mental health awareness.
A video of their powerful exchange -- conducted via FaceTime -- was released on the British Royal Family’s Facebook page and Gaga’s social media early on Tuesday, April 18.
William was inspired to speak with the pop star after reading an open letter she wrote in 2016, revealing her struggle with post-traumatic stress disorder.
Gaga was diagnosed with the illness after being raped at 19.
"I read your open letter you wrote the other day, and I thought it was incredibly moving and very brave of you to write down such personal feelings,” William said. "I wanted to ask you how you found speaking out and how it made you feel."
The Grammy-winning artist admitted that the prospect of sharing her story with the world left her “very nervous,” but she was compelled to speak honestly and openly about the important issue.
WATCH: Prince William and Lady Gaga do their bit for mental health awareness. Post continues...
"It made me very nervous at first, for me waking up every day and feeling sad and going on stage is something that is very hard to describe. There is a lot of shame attached to mental illness, you feel like there is something wrong with you,” she said.
“Even though it was hard, [it was] the best thing that could come out of my mental illness was to share it with other people and let our generation, as well as other generations know that if you are feeling not well in your mind that you’re not alone and that people that you think would never have a problem, do.”
William was quick to praise the multihyphenate talent for bravely opening up about her journey.
"It's OK to have this conversation. It’s really important to have this conversation. And that you won't be judged," William told Gaga. "It's so important to break open that fear and that taboo, which is only going to lead to more problems down the line."
He added: ”It's time that everyone speaks up and really feels very normal about mental health, it's the same as physical health. Everybody has mental health and we shouldn't be ashamed of it and just having a conversation with a friend or family member can really make such a difference."
The four-minute video is the latest film in the #OkToSay series, an initiative launched by the Heads Together foundation, which shows people from all walks of life discussing their own mental health challenges.
Heads Together is an organisation spearheaded by Prince William, his brother Prince Harry, and his wife the Duchess of Cambridge.
The candid conversation follows Prince Harry’s admission that counselling helped him deal with his late mother, Princess Diana's, death.
The 32-year-old told Bryony Gordon for her Mad World podcast that he was “very close to a complete breakdown on numerous occasions.”
Harry also revealed his older brother Prince William urged him to get professional help, telling him: “Look, you really need to deal with this. It is not normal to think that nothing has affected you.”
Harry says it was “only two years … of total chaos” before he felt comfortable expressing his feelings.
“I just couldn’t put my finger on it. I just didn’t know what was wrong with me.”
The young royal, who is often referred to as the People’s Prince, says seeking help has left him in a "good place."