The pop star was once again in the building at Arrowhead Stadium Sunday to catch the K.C. Chiefs play one last home game against the Cincinnati Bengals ... and just like she usually does, she rolled up in a golf cart down below and made her way to her luxury box suite.

Looks like she was cruising solo this time around, whereas last week ... she had some company in her mom and brother, who joined her for the big Christmas game there in town.

T-Swift was looking pretty stylish here for the NYE matchup ... dressed in all black, aside from a sweet white Chiefs letterman jacket she was rocking as she made her way up to the stands. If it wasn't obvious by now, she'll be spending New Year's there in Kansas City.

Like we said, Taylor attending games has become a bit of a pastime this year -- ever since she and TK went public with their relationship toward the start of the season ... she's gone in person to watch him several different times, and sometimes in totally different cities too.

At each stop, Taylor has been seen rooting and screaming her heart out for her man ... oftentimes memorably, whether it's cursing at a bad call or celebrating with handshakes.

While she and Travis were apart for a bit during Thanksgiving -- when she jetted on down to Brazil for a few shows as part of her 'Eras' tour -- they've spent the majority of the holidays together ... and their bond is going strong. From the looks of it, this could be the real deal.

From the NFL side ... you best believe the league has loved them as a couple, especially when Taylor shows up in person. The ratings have ballooned at most of her games ... as she seems to have drawn in a whole new audience who might've otherwise not watched.

Some diehard football fans have become annoyed with the attention Taylor commands -- but hey, it's entertainment at the end of the day ... and this is where worlds collide for big $$$.

Anyway, it's pretty safe to say she's probably had the biggest year out of anyone in showbiz.