Prince William has starred as a cover boy for the UK's leading gay magazine, Attitude.
William - the first member of the Royal Family to be photographed for the cover of a gay publication - told the magazine: "No one should be bullied for their sexuality or any other reason."
He had invited the magazine to bring members of the LGBT+ community to Kensington Palace in May to listen to their experience of bullying and the mental health affects it can have.
Speaking to Attitude, the Duke called on young people being bullied for their sexuality to seek help.
"What I would say to any young person reading this who's being bullied for their sexuality: don't put up with it - speak to a trusted adult, a friend, a teacher, ChildLine, Diana Award or some other service and get the help you need.
"You should be proud of the person you are and you have nothing to be ashamed of."
Attitude editor Matthew Todd, who led the meeting with William at Kensington Palace, welcomed the Duke's support.
"During my time as editor of Attitude I have met parents whose child has taken or lost their life after being bullied for being LGBT+ or even just perceived to be LGBT," he said.
"I am very happy that the future king of the United Kingdom agrees this must stop."
The Duke revealed he would be appearing in Attitude on Tuesday, after signing a book of condolence for victims of the gay nightclub shooting in Orlando which left 49 people dead and dozens of others wounded.
Nine members of the LGBT+ community told the Duke how being bullied had led to low self-esteem, suicide attempts, eating disorders, depression and drug addiction.
William said they were "brave to speak out" and "give hope" to others suffering.
Research published in 2015 showed that a third of young lesbian, gay or bisexual people and 48% of trans young people in England had made at least one suicide attempt, compared with 18% of young straight people.
Around 57% of LGB young people and 85% of trans young people had self-harmed at least once compared with 38% of young heterosexual people and 47% of cisgender young people - those born into the body that they feel they are.
The July edition of Attitude magazine is available to download now from pocketmags.com/attitude - or to buy in shops from June 22.