Her name means "she of the Shesmet-girdle", and she was probably first worshipped at a town with the same name, a few miles away from Bubastis, now called Saft el Henneh. She had a staff of priests with an overseer, perhaps including "the Shesmet-girdle man", who probably wore the girdle - "a leather belt from which were suspended narrow strips of hide ending in tassels", sometimes with ornaments like beads or shells. (The gods Horus, Set, Thoth, Amun, and the centipede god Sepa could also be depicted wearing it.)
Shesmetet is grouped with other lioness goddesses in the Pyramid Texts (Utt 262 - "King Unis is conceived by Sekhmet, born of Shesmetet"), on a monument of the Thirteenth Dynasty pharaoh Sobekhotep IV, on Eighteenth, Twentieth, and Thirtieth Dynasty monuments (with Bastet and Wadjet), and as a form of Mut on an Eighteenth Dynasty statue.
(ETA: Newberry footnotes the Sobekhotep monument as "Louvre C. 11.", but that reference took me to one of the stelae of Ameniseneb. Confusion.)
Apparently Nubian and other African women wear an identical girdle to this day. I'm interested in ways African cultures outside of Egypt might have influenced Egypt; given its antiquity, I wonder if this might possibly be an example. (Or perhaps it was simply an item of clothing common throughout the area.)
"Newberry, Percy E. The Shesmet-girdle or Apron. Egypt Exploration Society. "Studies presented to F. Ll. Griffith". Milford : Oxford University Press, 1932.