“NOT MY PANTS RIPPED ON LIVE TV,” he tweeted later. “OMFG NO.”
The rapper and singer – whose real name is Montero Lamar Hill – attributed the tear to his stripper-pole routine on stage.
The accident is obvious in the video of the performance, as he looks down in surprise when it happens, and he quickly uses his hand to try to cover the damage.
The two-time Grammy winner, 22, triggered homophobic outrage among conservatives in March with his video for Montero, which included Lil Nas X grinding on the devil in a fantastical hell.
Montero debuted at number one in both the US and UK upon its release last month.
The hell-evoking SNL performance recreated some of the same elements as the video.
Lil Nas X also performed his new single Sun Goes Down, about the pain of being a closeted adolescent, on SNL, but it wasn’t quite so dramatic.
Check out Montero up top and Sun Goes Down below...