Swift, 35, shared a photo of Kelce, 35, on one knee as well as a photo of her engagement ring.
Kelce, the Kansas City Chief tight-end, proposed to Swift in a flower-filled garden underneath a decorative arch.
The pair have been dating since 2023.
Posting a series of pictures with the Super Bowl-winning American footballer she wrote: “Your English teacher and your gym teacher are getting married.”
Within 10 minutes of the post being published it racked up more than 1.3 million likes.
Swift has more than 11 million followers on Instagram.
The other photos show Mr Kelce and Ms Swift hugging. In one, she holds his face as they smile at each other.
Another photo showed the engagement ring, featuring what appears to be a huge diamond
In an interview with GQ earlier this month, Kelce suggested Swift’s drive and success, which has seen her become one of the world’s most successful artists, was one of the things that brought them together.
The Chiefs player has been thrust into the global spotlight since their romance was publicly confirmed.
The pair made it official with an appearance from Swift at one of his games in September 2023, when she joined her boyfriend’s mother in a VIP suite.
