Lady GaGa allows Philip Treacy to be "really creative" with his designs.
The British milliner - who long collaborated with the 'Judas' singer - loves working alongside her because she has no limits and will allow him to go crazy with his creations.
He said: "She's a really fun person to work with. She has a different sensibility - a different idea of what's perfect and beautiful.
"She allows me to be really creative and brings my designs to a whole new audience."
She even took part in his London catwalk show recently, and he was shocked when she herself suggested it - even though it meant she had to fly from Dublin to the British capital to take part.
He told vogue.co.uk: "I went to see Lady GaGa backstage after seeing her at Twickenham for the 'Born This Way Ball', and I was telling her about the show and then she just suggested it.
"It was all her idea. She was going to be in Dublin the night before, so she said that she'd fly over for it. Playing to 80,000 people on one night and then appearing in my show the next? Amazing. Of course I agreed."