The treatment isn't offered on the NHS, but it's understood some staff have occasionally put patients in touch with organisations who provide it.
Experts say attempting so-called "gay cures" can be "dangerous" and "damaging".
Fourteen organisations, including NHS England, have signed an agreement to stop gay conversion therapy being offered to patients.
Although in general, referrals to conversion services are rare - there is evidence that GPs, counsellors and psychotherapists have made them.
They will also be providing training for staff to enable them to improve support available to lesbian, gay and bisexual (LGB) people seeking advice.
The agreement, The Memorandum of Understanding on Conversion Therapy in the UK, makes it clear that NHS England, the organisation which has day-to-day responsibility for running the NHS, "does not endorse or support conversion therapy" and will make this clear to staff.
It essentially means GPs will not be able to refer patients for gay therapy and that no-one employed by the NHS can provide it.
Amber Dowell, communications officer at the UK Council for Psychotherapy, told Newsbeat the agreement was "really important".
"It's very common for people to have feelings where they might question their sexuality, where they might want to explore the attractions they're feeling.
"We want people to be able to do that in an environment that is safe, supportive and free of judgement."
There are no official figures for how many people attempt conversion therapy every year, but the Department of Health has acknowledged to Newsbeat it does occasionally happen.
Amber suggested that an "ignorance of the issue of the ethics involved" rather than staff being "prejudiced against LGB people" was to blame for it being offered by the NHS in the past.
"I think, in trying to help people mistakenly, referrals had been made in the past," she said.
Newsbeat has spoken to people who said they had experienced conversion therapy.
Louise from West Yorkshire said she was blackmailed into receiving "treatment" for being gay in 2007 by her evangelical church.
She later attended group sessions of around 20 women near Liverpool. "[Most] were married with children. They were there without the knowledge of their partners or their children.
"If I'd been more impressionable I think I could have been really damaged by the process."
Brad, from Illinois, lives in the West Midlands. He said he was "scared" when he first discovered he was gay and "wanted to do my very best to change it".
He attended group therapy sessions but realised the treatment, which he said encouraged him "to do more stereotypical masculine things" wasn't going to change his feelings.
"It's really sad I spent three years of my life trying to do something that was impossible."
There are some who suggest it works and insist people should be able to try it.
Mike Davidson told Newsbeat he "converted" with therapy over the course of two years and now provides what he calls "support" for people who have "unwanted same-sex attraction" in Northern Ireland.
He thinks the service should be allowed but he wasn't able to give an accurate estimate of how widely the treatment was available.
He told Newsbeat that gay conversion isn't a "huge industry" and that the people he works with have decided it is something they want to do.
"By the time they [clients] get to us, they know what we're about and know what they would like to achieve."
Explaining the process, he said: "For some people they want to go as far as controlling their behaviour... they do not want to act out on those issues and we would support them."
He also said that he turns people away who appear to have been pressured into taking therapy and admitted that, even when working with someone who wants to change their sexual feelings, a "result" is never guaranteed.
The UK Council of Psychotherapy says it intends to expand the agreement to Wales, Northern Ireland and Scotland soon.
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NHS staff in England have been told that they should no longer help people access gay conversion therapy.