A student at a Catholic boys school got a standing ovation when he came out as gay during a speech at assembly.

Finn Stannard, a Year 12 student at St Ignatius College Riverview, in Sydney, told 7.30 he gave the speech for his "younger self".

"I've been working towards this speech for four years," Mr Stannard said in front of 1,000 students.

"In those four years, I have come to understand who I am and how to not be sorry for being myself.

"Outside home, being gay has not always been easy. I have been the subject of countless rumours and unpleasant jokes.

"Telling friends was difficult and came with a lot of anxiety. My main fear was no longer being accepted or losing my friends and being the subject of derogatory jokes."

Sorry, this video has expired Finn Stannard's full speech at St Ignatius College Riverview.

Mr Stannard told 7.30 he was overwhelmed to receive a standing ovation from his peers.

"I felt like I was part of that community again," he said.

"I felt like I had gotten this chance to be the real me and people accepting me for that. That was just the best feeling in the world.

"I wanted to do it for my younger self. I didn't have a role model in school who I could follow to help me understand who I was, how I should behave, how I should be able to be me."

'Mum, I think I might be gay'

Finn Stannard with his mum Meaghan Stannard. ( ABC News: Nadia Daly )

Mr Stannard said the love and support of his family and boyfriend helped give him the courage to make the speech.

His mother was the first person he came out to.

"I said, 'Mum, I think I might be gay'. While she was definitely surprised she was by no means overwhelmed. She gave me the biggest hug and she kissed me and said she loved me," he said.

"That was when I knew I'd be fine in everything that came my way. I always knew I had a supportive family."

His parents were at first worried about his plan to come out in front of the entire student body.

"Not everyone can be kind about a young man taking on his identity and being proud of who he is," Meaghan Stannard said.

"So we were concerned about the feedback he might get from his speech."

Finn Stannard, right, with his boyfriend Thomas Moiso. ( Supplied: Finn Stannard )

His boyfriend Thomas Moiso helped him practice the speech.

"Thomas has been amazing throughout the whole experience. He literally and metaphorically held my hand through the entire situation," Mr Stannard said.

Mr Stannard took Mr Moiso as his date to his Year 12 formal.

Mr Stannard says everyone at school has been "so supportive".

"They were so supportive. The school has been amazing. They've supported me the entire way," he said.

Next year Mr Stannard will start a teaching degree at university. And he will be following the public debate over the right of religious schools to hire and fire teachers on the basis of their sexual orientation.

"People should be hired for the job if they're the best for job. Sexuality has nothing to do with that. It's all about how they can help students learn and get the abilities to be themselves," he said.

