Taylor Swift has finally been outshined ... and of course, she did it to herself.

TS gave a great Grammy Museum performance on Tuesday night ... but her massive wedding ring from Travis Kelce stole the show.

See for yourself, because all 7 minutes and 50 seconds of her show have finally been released for the masses.

Tay played a mashup of "I Knew It, I Knew You" and "All Too Well" on her trusty Eras Tour piano ... and it's a wonder she could even lift her left hand to play it under the weight of that rock!

As every fan knows ... Taylor's wedding ring is an 8 to 10-carat antique old mine brilliant-cut elongated cushion diamond.

Talk about rocking out with your ... rock out.