Check it out ... the Grammy winner smiled wide after she clocked the Kansas City Chiefs tight end in the crowd at her 3rd show at the Aviva Stadium in Dublin.

TK was at a California wedding over the weekend ... rushing to Europe to catch at least part of her Sunday concert in Ireland. Travis arrived in time for the "Folklore" era, as she performed her hit "August" in a red, flowing gown onstage.

Taylor pointed at Travis from the stage ... and he responded with a sweet little wave.

Dedicated Swifties are convinced Travis surprised Taylor at the "Eras" tour stop ... citing her body language. The couple linked up backstage at Aviva Stadium ... where Travis was filmed showering his GF with all sorts of praise.

Travis, who began dating Taylor in July 2023, has been a fixture at the singer's record-breaking tour. He attended all 3 nights of her London stop at Wembley Stadium ... even joining her onstage once for the "Tortured Poets Department" era of her setlist.

The football star was joined by his family at the "Eras" tour ... as his brother Jason Kelce and sister-in-law, Kylie Kelce mingled with him and the royal family -- including Prince William, Prince George and Princess Charlotte.

Of course, Taylor has shown the same support for Travis' football career ... showing up for a number of his games last year. The couple even shared a sweet moment after Travis' Super Bowl win in February.