The 'Bad Romance' singer shared her happy news with fans via Instagram, saying Taylor had popped the question on Valentine's Day and she had happily accepted.
Gaga also shared a photo of her heart-shaped diamond engagement ring.
"He gave me his heart on Valentine's Day and I said YES!" she said.
Gaga – real name Stefani Germanotta – has been dating Taylor for around four years, after they initially met on the set of her 'You and I' music video in July 2011.
She previously told Ryan Seacrest's radio show: "In this gypsy life that I live, when you're able to meet someone that, you know, neither one of you wants to change one another, and you're both on your respective journeys… But then, you meet in the desert somewhere and you fall in love."
Taylor, 33, is best known for his roles in Chicago Fire and Chicago PD. He has also appeared in The Vampire Diaries.
Congrats to Gaga and Taylor!
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!