Wallis said he was suffering from post-traumatic stress after being raped last year.
Conservative MP Jamie Wallis has become the first-ever UK lawmaker to come out as transgender.
Wallis -- who represents the Welsh constituency of Bridgend -- was praised across the political spectrum after revealing he wanted to change his gender.
“I’m trans. Or to be more accurate, I want to be,” Wallis said in a statement on Wednesday.
“I’ve been diagnosed with gender dysphoria and I’ve felt this way since I was a very young child,” the 37-year-old added.
“I have never lived my truth and I’m not sure how,” Wallis said, "perhaps it starts with telling everyone."
The Tory MP also revealed that someone was jailed for trying to blackmail him in April 2020 for £50,000 (€59,000).
Wallis said he was still suffering from post-traumatic stress after being raped last September.
"I have not been myself since this incident and I don’t think I will ever recover," Wallis said. "It is not something you ever forget, and it is not something you ever move on from."
UK Prime Minister Boris Johnson began his weekly question session in the House of Commons by issuing a message of support to the Conservative MP.
"The House stands with you and will give you the support that you need to live freely as yourself,” Johnson said.
That support was echoed by other politicians, including opposition Labour Party leader Sir Keir Starmer.
Former UK Chancellor George Osborne said on Twitter the reaction to Wallis’ “brave” statement reflected progress in the UK's ruling party.
“If a Tory MP had said this when I was first elected 20 years ago they would have been hounded, not applauded and supported,” Osborne said.
PM Johnson’s government has resisted recommendations from MPs to make it easier for people to change their gender by removing the requirement to have a medical diagnosis of gender dysphoria first.
According to multiple media reports, Johnson also opened a recent Conservative party by saying: “Good evening, ladies and gentlemen, or as Keir Starmer would put it, people who are assigned female or male at birth.”