"It's fantastic to have Madonna, especially for the Eurovision," Gaultier said outside the Tel Aviv venue of the 2019 songfest.
The French designer said his inspiration came from one of his own countrywomen.
"Kind of Joan of Arc, you know? Because she is like a winner - a winner, kind of. A warrior, let's say," he said, smiling.
"Twenty years, thirty years ago (Madonna) didn't know what was Eurovision, and now she’s singing there."
Madonna was scheduled to perform two songs at the music competition - new number "Future" and her 1989 hit "Like A Prayer."
The 60-year-old "Queen of Pop," known for repeatedly reinventing herself, has faced criticism for performing in Israel - pro-Palestinian groups have urged musicians to shun the event to protest Israel’s policies in the West Bank and in Gaza.
Israel says the boycott calls are discriminatory and anti-Semitic, which boycott activists deny.
In a statement earlier this week, Madonna explained her decision to attend, saying she would always speak up to defend human rights and that she hoped to see "a new path toward peace."
Gaultier has collaborated with the music superstar for decades, from her iconic conical bras to the glitzy Met Gala in New York.His work with Eurovision is also long-standing: he has dressed previous winners Dana International and Conchita Wurst.