The GRAMMY winner's humility explains why they're able to work so well together. Maxwell was the man behind Gaga's three jaw-dropping Oscar looks, which ruled the night at Hollywood's biggest event.
Maxwell said that her collared menswear look had to be just perfect for her performance of "Til It Happens to You," the Oscar-nominated song from the college sexual assault documentary The Hunting Ground.
"It's so personal to her, that song, and it's so personal to so many different people," Maxwell said. "I really wanted to be respectful and so did she."
Gaga belted out the tune while several sexual assault survivors gathered around her on stage.
Maxwell has his own fashion brand and he told ET that he actually created a fourth Oscar dress for Gaga in case she won.
"That was actually a look from the [Spring 2016 fashion] show. We did a black velvet strapless mini dress with a little peplum on the side," Maxwell said. "For her we did it in a celery velvet that was a long gown."