The 26-year-old singer debuted her new look on Twitter, calling the shade "Louis Vuitton brown".
GaGa posted a series of tweets with a picture of her new chestnut-coloured locks and explained why she had made the decision to ditch her trademark blonde hair.
She told her fans: "I'm gonna leave one streak of bad by my left ear. Lady when its down, and GaGa when its up. could we belong together?
"Definitely feeling less blond lately and little more progressive brunette. I am LOUIS VUITTON BROWN. BITCH THATS LV."
She later added: "i think I'm gonna do away with this blond streak, feeling like a purist. gosh i forgot what it was like to have soft hair!"
She showcased her new hairdo for the first time in public when she landed in Vilnius, Lithuania, as part of her 'Born This Way' European tour.
Watch the video for Lady GaGa's 'You And I' below: