Three years after Travis Kelce was drafted into the National Football League, the tight end courted 50 contestants, one from each state, for a “Bachelor”-esque dating show on E! Entertainment that drew little notice.

His profile has risen substantially since “Catching Kelce” aired in 2016. He has won two Super Bowls with Kansas City — catching a touchdown in each — and earned eight Pro Bowl selections while dabbling as a media personality, hosting a “Saturday Night Live” episode and helming a popular football podcast.

But in terms of maximizing his celebrity, nothing compares to Kelce’s brush with the aura of Taylor Swift, a 12-time Grammy winner whose Eras Tour this year has shattered concert records and even registered seismic activity.

If you live in the New York City area and will be watching your first football game on Sunday night when the Chiefs and Travis Kelce take on the New York Jets, we would like to be there. Let us know about your plans.*

Kelce and Swift, both 33, have remained quiet about whether they are friends or a couple, or just two celebrities trying to leverage each other’s fame. But fans regularly dissect Swift’s dating life and failed relationships, which she has written about in her own songs.

After weeks of speculation about a connection between Kelce and Swift, who broke up with the actor Joe Alwyn this year, she attended Kelce’s game at Arrowhead Stadium in Kansas City, Mo., on Sunday, watching from a luxury suite with his mother as the Chiefs trounced the Chicago Bears. Fox cameras panned to Swift’s reaction nearly every time Kelce touched the ball. The singer’s devoted swarm of fans also tuned in, with several posting on social media that they were watching football for the first time.

Swift, wearing a red-and-white outfit that matched Kansas City’s colors, was then seen leaving the stadium with Kelce.

Despite Kelce’s relative fame in the sports world, becoming part of the frenzied conversation around Swift’s every move is another ballgame. Kelce now has 3.2 million followers on Instagram. Swift has 273 million.

“This puts him on a completely different plane from where he was as a celebrity,” said Daniel Durbin, a professor of communication at the University of Southern California. “This is celebrity on steroids, and it has a powerful impact.”

As professional athletes near retirement in their 30s and early 40s, many begin to plot their next career moves. Some become broadcasters, while others turn to Hollywood. LeBron James, the star basketball player, has started his own tequila brand and said he wants to own a team.

That Kelce and Swift were in the same stadium this weekend brought together two fandoms that don’t often overlap. A spokesman for Fanatics, the N.F.L.’s official retailer, said that sales of Kelce’s jersey had spiked by 400 percent as of Monday.

Coaches and players from across the N.F.L. also took notice.

Bill Belichick, the Patriots coach known for gruff answers to reporters’ questions, said on a radio show that “Travis Kelce’s had a lot of big catches in his career — this would be the biggest.” The star Cowboys defender Micah Parsons posted on X, formerly known as Twitter, that one woman “can change your life!!!”

Celebrity relationships in the N.F.L. are not new, but they are normally reserved for star quarterbacks who touch the ball every play. Russell Wilson married the singer Ciara in 2016; Tom Brady, who won seven Super Bowls, spent 16 years with the model Gisele Bündchen before they divorced last year.

It is rarer, but not impossible, for a tight end to drive the national conversation. But Kelce, propelled by his stylish outfits, trimmed beard and haircut and his charismatic personality, has emerged as one of the N.F.L.’s most marketable stars. Before Swift, his fame had crescendoed because of a candid podcast he hosts with his brother, Jason, the center for the Philadelphia Eagles. (Their relationship was a popular topic before last season’s Super Bowl, in which the Chiefs narrowly defeated the Eagles.)

On their weekly podcast, “New Heights,” the Kelces discuss their lives as professional athletes and speak with high-profile guests like Chiefs quarterback Patrick Mahomes and N.F.L. Commissioner Roger Goodell. It was also where the Kelce-Swift story line began.

In July, Travis Kelce said on his podcast that he had wanted to give Swift a friendship bracelet during her concert tour stop in Kansas City, but that she had declined to meet him in order to save her voice. Last week, amid rumors that the celebrities were dating, Kelce confirmed in an ESPN interview only that he had invited Swift to a game.

“I told her that, ‘I’ve seen you rock the stage in Arrowhead. You might have to come see me rock the stage in Arrowhead, and see which one’s a little more lit,’” Kelce said.

Whatever happens with Kelce and Swift, the attention could be benefiting them both.

Her concert movie, “Taylor Swift: The Eras Tour,” releases next month, and he is already pursuing a career outside sports. He told The Los Angeles Times this summer that he considered Peyton Manning, the Hall of Fame quarterback and founder of the content company Omaha Productions, a mentor, and he recently signed with the powerful media conglomerate Creative Artists Agency.