"I don't want to be called gay, because I'm simply a man... full stop," the 55-year-old said in an interview with Italy's Corriere della Sera daily.
"The word 'gay' was invented by those who need to label people, and I don't want to be identified by my sexual choices," he said.
Gabbana launched the luxury fashion label in 1984 with his partner Domenico Dolce, and although they separated in 2004 the couple continued to work together.
"I thought that I could help spread a new culture as a famous person, a culture no longer based on gay rights but on human rights. We are human beings before being gay, heterosexual or bisexual," Gabbana said.
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The Milanese couturier said gay associations "often serve as a defence, but I don't want to be protected by anyone, because I've done nothing wrong".
He said he realized he was homosexual aged 18, when his girlfriend "who I really liked" came to visit him for a weekend in Milan, but when they went dancing he "was watching the men more than her".
"I had known (about being gay) for a while, but I didn't have the courage to admit it. Only through therapy did I realize that there had been clear signs in my childhood.
"I wanted to play alone... because I felt different from the other children and I feared that if we were together they would realize. And they would tell my mother," he added.