De Bruyn was born in 1914 in Erembodegem, East Flanders, Belgium with both male and female sex organs.
In the evenings, he secretly began reading about his condition in medical literature by e.g. Magnus Hirschfeld as well as mythological and anthropological studies.
However, as he was still registered as a woman named Elvire, he repeatedly came into trouble and lost jobs which were not considered acceptable for women, such as working in a hotel kitchen.
In 1965, Willy de Bruijn was selling "smoutebollen" at the Belgian village at the New York World's Fair.
[6] On 4 August 2023, Google celebrated De Bruyn's 109th birthday through a doodle, featured as a replacement of the Google Logo in that day for devices at Belgium[7] On 25 July 2024, The New York Times published a belated obituary for De Bruyn in their Overlooked No More series.