New rules that have recently come into effect allow transgender people born in the province to apply to have the document amended by submitting a letter from a practising physician or a psychologist.
Susan Gapka, chair of the Trans Lobby Group, hailed the change as a crucial step for the transgender community in having their gender identity recognized.
"We're going to celebrate this victory — because it is a victory, it's a giant leap forward," she said.
"Trans people's identification will more easily match their presentation to the public."
Ontario is the first province in Canada to scrap the requirement.
It stems from a ruling by the Human Rights Tribunal of Ontario this April in the case of a born-male woman known as XY.
The tribunal found the legislation requiring proof of "transsexual surgery" to alter birth documents to be discriminatory.
In its ruling, the tribunal said the requirement added to the stigma felt by members of the transgender community and reinforced stereotypes surrounding how they experience gender.
Gapka said the birth-certificate change is the latest success for the community, which in June saw its legal status clarified with an amendment to the Ontario Human Rights Code that extended protections to transgender people.
After years of legal ambiguity or outright denial of their rights, transgender people are being recognized like other minority communities, Gapka said.
"Finally trans people are gaining access to their legal rights...we're catching up to other disadvantaged groups," she said.
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