The spike in sales comes one day after Swift showed up to cheer Kelce on during the Chiefs' game against the Bears.
Just one day after Swift came out to cheer him on at Arrowhead Stadium, as the Kansas City Chiefs took on the Chicago Bears, sales of Kelce's No. 87 jersey have reportedly shot through the roof.
The NFL's official e-commerce partner Fanatics told TMZ on Monday that Kelce "was one of the top 5 selling NFL players and saw a nearly 400 percent spike in sales throughout the Fanatics network of sites."
While it's not definitive that Swifties are the reason for the sudden spike, it does come after Swift's appearance at the game, where she was decked out in Chiefs gear, as she hung out and enthusiastically cheered for Kelce alongside his mom, Donna Kelce.
Swift's fun night in Kansas City didn't stop with the Chiefs' 41-10 victory over the Bears.
In a video captured after the game, the "Look What You Made Me Do" singer was full of smiles and waves as she and Travis exited the venue side-by-side, and then appeared to drive off together in the same car.
Their night continued at the popular family eatery Prime Social Rooftop, a trendy restaurant in Kansas City. According to an eyewitness, the athlete and songstress had a night of celebration.
"Travis bought out the restaurant for his family and team. Taylor arrived, wearing a denim dress, and was seen snacking, having some cocktails and dancing alongside Travis," the eyewitness said. "The two were very affectionate with one another but kept things fun and lighthearted. Travis' teammates also showed up to the after-party, as well as his mom and dad, Donna and Ed. The party lasted until 2 a.m."
A source told ET, "Travis has never shied away from his desire to give dating with Taylor a try, which he even said during a press conference a few months ago after seeing Swift in concert. Travis and Taylor are taking things slowly, and not rushing into anything serious. Both are very career-focused, so the focus is on that for now, but that's not going to stop them from enjoying life when it's the right moment."
Swift's NFL Sunday came after Kelce revealed that he'd recently invited the singer to watch him play after being wowed by her concert at the stadium during her Eras Tour.