William and Kate officially opened the organisation's new headquarters in Bute Mills in Luton on Wednesday and met with young people who have benefited from projects set up by the charity.
Greeting the royal couple, Youthscape CEO Chris Curtis said: "Your Royal Highnesses, we are deeply honoured that you are visiting today to mark the opening of Bute Mills.
"Thank you for coming and meeting some of the amazing young people we have the privilege of working alongside.
"They are, quite simply, rather fabulous, as I'm sure you've found. You have made this day unforgettable for them - and for us at Youthscape - and we are absolutely thrilled to welcome you here today."
The visit was part of their long running campaign to raise awareness of the difficulty those with mental health issues face.
Talking to a young person about the difficulties she faced when her mother died, William told her: "What happened should never have happened to you and you should never have gone through it.
"The fact you have gone through it and got where you are now, you should be really, really proud."
While at the charity the royal couple also unveiled a plaque to officially open the building which has recently undergone a £3m redevelopment.
While Kate told a group playing Uno, that the game was her favourite, William joined in a game of pool and a game of Fifa on a games console playing as his favourite team Aston Villa.
Speaking to Premier after meeting William and Kate - Ellis, who's received support from Youthscape said: "It's probably the scariest thing that's ever happened to me.
"I'm still shaking and I don't think I'm going to stop - ever.
"For [them] to take time out of their very busy schedules to come and listen to young people says so much about how much they value young people and how much they value young people's health."
Youthscape's Luton Director Alex Drew told Premier's News Hour she was encouraged to see the couple's heart for young people.
She said: "Today is good news for Luton and good news for young people across the whole country because I think they have a heart that really, really cares for young people.
"They really want to see change and they really want to spend time and energy in seeking change for young people and that's really exciting."
The Duke and Duchess of Cambridge also held discussions about mental health issues with Luton Council of Faiths, the OM Group and Our Minds Matter, as they talked about raising awareness and addressing stigmas in the area and communities.
Listen to Premier's Jamie Cutteridge speaking to Ellis and Alex Drew on the News Hour: