The Lover songstress -- who stunned at the premiere in a floral, ruby Oscar de la Renta satin gown -- was photographed heading out with her beau by her side, as they were shielded from the rain by men holding umbrellas.
While the 28-year-old Mary Queen of Scots actor didn't pose for pics with his ladylove before the screening, he turned out to show his support for the film, and their sweet departure was an adorable reminder of how cute the couple truly is.
While the pair have been dating since 2016, fans are still waiting for them to make their official red carpet debut together.
Swift, meanwhile, spoke with ET ahead of the premiere and while she didn't mention Alwyn -- or the fact that he was going to be there for her big night -- she opened up about her new musical and getting the chance to write and record and original song for the movie alongside the Broadway musical's legendary creator, Andrew Lloyd Webber.
"That alone was just a life-changing dream-come-true moment for me," Swift told ET's Rachel Smith of penning the tune "Beautiful Ghosts," which is sung in the film by Francesca Hayward -- playing the dancing cat Victoria -- while Swift's version will play over the film's closing credits.
"It's one of those songs that I feel like the movie doesn't make sense without that song. It's not like it was just a song that was stuck into the film," Swift explained. "This is a character that is a lead character in the film, and in the original Broadway production, she doesn't have a song."
"In the production she's just a ballerina, we don't ever hear from her," Swift continued. "So it was amazing to get to be the lyricist who figured out what she was going to say when she spoke."