Prince William visited the Centrepoint Helpline in London to meet with its current advice workers
He will also join a training session for new recruits on how to handle and manage calls through the service.
According to Centrepoint research, more than 150,000 young people a year across the UK approach their local councils for help with housing, with a third turned away without meaningful support.
There is currently no single source of information for young people who are at risk of homelessness.
According to a YouGov poll commissioned by Centrepoint, 17 per cent of young people young people have at some point felt they had nowhere safe to call home.
The Duke of Cambridge will join a training session for new recruits on how to handle calls
We take the first step towards realising our ambitious goal to end youth homelessness before it has even begun
Seyi Obakin, Centrepoint’s Chief Executive
As a result of this, 65 per cent have sofa-surfed, 35 per cent have stayed where they were living even though it was not safe, and 31 per cent have slept in an insecure place, for example, on the streets, in a car or tent, or squatted.
The Centrepoint Helpline is a Freephone number, supported by BT, for any young person aged 16-25 worried about homelessness. Support will be available online, over the phone, via text and via email.
Prince William's helpline has so far helped 116,000 young vulnerable people turn their lives around
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Advice line workers will be able to offer advice and support on housing issues, as well as issues that impact on housing situations, including mental health, relationships and finances.
The Duke of Cambridge has been patron of Centrepoint since 2005, following in his mother’s footsteps.
Centrepoint is the leading charity for homeless young people and since 1969 has helped more than 116,000 turn their lives around.
The charity provides more than a safe place to stay, including help to access education, employment or training and vital support in tackling the physical and mental health problems caused by homelessness.
Seyi Obakin, Centrepoint’s Chief Executive, said: “It is clear wherever you look in our towns and cities that homelessness is reaching a crisis point.
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“And it doesn’t stop there. Centrepoint’s research shows that for each one of those young people on the streets, dozens more are sleeping on the sofas of extended family and friends and, in some cases, in the beds of strangers.
"Some of these young people will have fled constant family arguments or violent partners, others will have exhausted the generosity of friends and find they have nowhere else to turn.
William has been patron of Centrepoint since 2005, following the footsteps of his mother
“It doesn’t have to be this way. Intervening early and decisively by providing the right support for those in crisis can end youth homelessness.
"Today, with the launch of the Centrepoint Helpline, we take the first step towards realising our ambitious goal to end youth homelessness before it has even begun.”