The couple has been dating for more than two years, and have remained fiercely private about their romance. However, Taylor couldn't resist gushing about "The Favourite, which stars her beau as the lovestruck Samuel Masham.
"AHHHHH @thefavouritemovie just won 7 @bafta awards !!! Bout to go give some high fives - thanks @stellamccartney for this dressss," Taylor, 29, shared on Instagram. In the snap, the "Shake it Off" hitmaker is wearing the stunning baby blue custom creation, with her hair in chic waves and clipped behind her ear with a hairpin.
While Joe was at the prestigious ceremony held at the Royal Albert Hall in London on Sunday night (February 10), the singer opted instead to join her boyfriend at the BAFTA dinner, held at Grosvenor House.
The couple was later photographed leaving the star-studded bash, with Taylor wrapping up warm with a baby blue Max Mara belted coat over her Stella McCartney tulle dress.
Joe and his pop superstar girlfriend then headed to Annabel's in Mayfair for the Vogue and Tiffany & Co Fashion and Film Party, according to Mail Online.
"The Favourite" won Outstanding British Film at the BAFTAs, as well as Best Original Screenplay, Best Costume Design, Best Production Design and Best Hair and Make-up.
The movie is up for 10 Academy Awards later this month, with Olivia, Rachel and Emma Stone up for acting honours, and Yorgos Lanthimos nominated for Best Director.