Taylor Swift's ready to watch her man take care of business against the Denver Broncos ... pulling up to his Sunday afternoon game in K.C. in a biz-casual ensemble.
The singer-songwriter rolled into Arrowhead Stadium in a red and black checkered blazer, pulled over a low-cut black top ... with a tiny skirt matching her jacket.
Clearly, she's in her "No-Nonsense Era" ... preparing to watch her boyfriend Travis Kelce's team beat up on their division rival.