Williams was born Karen Louise McGlashan[2] on April 16, 1963, in Syosset, New York.

Williams grew up in Freeport, New York, and graduated from Baldwin Senior High School.

Williams argued multiple management-side cases before the National Labor Relations Board.

[10] Progressive magazine The American Prospect criticized Williams' nomination, saying "Williams spent many years as a management-side labor and employment attorney, even arguing cases against workplace sexual harassment claims, a troubling background to those hoping for judicial appointments that might defend workers.

[12] On October 26, 2021, the United States Senate invoked cloture on her nomination by a 58–40 vote.