"Every day on This Morning, I sit in awe of those we meet who have been brave and open in confronting their truth – so now it's my turn to share mine. This will probably all come as something of a surprise and I understand, but only by facing this, by being honest, can I hope to find peace in my mind and a way forward."
He has asked people to be kind, "especially to my family".
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Schofield has dual British and New Zealand citizenship. He grew up in New Zealand and began his career in TV here before moving back to the UK.
In New Zealand, he had his first TV job as the initial presenter of the youth music programme Shazam! in 1982. He also spent two years working for Radio Hauraki, before moving back to the UK in 1985, where he became the first in-vision continuity presenter for Children's BBC on weekdays.
Schofield and his co-host Willoughby appeared at the beginning of Friday's This Morning show, which was presented by Eamon Holmes and Ruth Langsford, to discuss his announcement.
He said he's decided to go public with his announcement because "all you can be in your life is honest with yourself and I was getting to the point where I wasn't being honest with myself and I didn't like myself very much because I wasn't being honest with myself".
He realises this brings "pain and upset" to his family but adds that they are supportive of his decision and he feels "lighter" since making the announcement.
"The thing is you know this has been bothering me for a very long time, everybody does these things at their own speed, when they think the time is right. It has consumed my head, and has become an issue in my head,' he said.
Schofield has received a wave of support from family, friends and fans.
Actor and comedian David Walliams posted on Twitter: "I am sending all my love to Phillip Schofield today. I have always held him in the highest regard, and now have nothing but respect and admiration for him. Let's hope we are moving towards a world where no one has to come out any more, they can just be who they are and celebrate that."
Celebrity stylist Gok Wan commended Schofield's "bravery.